Category Archives: Free Materials

Free Materials







          The very fundamental reason behind this project is to expose students to the very important aspect of private and independent research work. Not only in theories but also subsequent translation of theoretical research work into a practically functional system.

This project the design and construction of an automatic generator switch has been done primarily as a proto type design. It could be further modified to switch other application when desired. Eg it can be connected to electric motor, which was attached to a sliding door to achieve automatic control of the door when a person approach, the door or an alarm bell to give a warning signal to the occupant of the house.

This thesis will prove a valuable aid to those who may wish to embark on project involving photo-devices.






1.0     Introduction                                                                   1

1.1     Statement of Problems                                                   2

  • Aims and Objective 3
  • Limitation of the Project 3
  • Literature Review 4

2.1     Historical                                                                       5

  • Theoretical 6
  • Design and Construction 8

3.1     Design Method                                                              8

  • Circuit Diagram and Description 9
  • Constructional Method                                       16


  • Basic Principles of Operation the Components,

Description and Uses                                                     18

4.1     Modification of Resistors                                              19

  • Method of Reading the Color Code 21
  • Transistors 27
  • Diodes 32
  • Light Emitting Diodes 36
  • Mode of Operation of the (LED) 37
  • Transformer 38


  • Conclusion and Recommendation 44

References                                                                      45

Appendix                                                                                46





In the earlier days of the electronic age virtually all the operation of electrical and electronics gadgets were manually operated. Nowadays, most of these contrivances are operated atutomically. A typical device that brings about automatic operation of an automatic electronic generator starting switch. This device helps to reduce labour cost instead of some one being employed, switching the circuit on and off light when there is power failure the automatic switch does that automatically. Secondly, the most important application of this device is for security purposes. This is discussed fully in the chapters of this project.

The automatic generator starting switch works solely on the principle that some material such as selenium cadium sulphide. Selenude and indium automnida here their resistance altered when light falls on them i.e. when (illuminated). This leads us to the most vital components of the device known as light dependent resistor (LDR). If properly connected with a transistor or IC as the case may be and eliminated its resistance will kary. This variation in resistance of LDR will cause a subsequent voltage change at the input – of the transistor there by swinging the transistor into on or off state as the case may be.

This device can be used to operate street lights, security lights or even zoom lights automatically i.e. its puts the lights on when night approaches and put it off in the morning. It can be used to activate burglar house when an intruder transposes illumia path. The device can be used to sound warning signals from an alarm for safety of Industrial machines when one crosses the eliminating path. It can be used in automatic car parking light and an automatic curtain this device mainly used or employed to switching on a generator at might light in the morning.



There is the need for the Nigerian scientists and engineers to try out the production and repair of the existing equipment. This is due to the present economic squeeze facing the country and this project will provide a casting solution to power change over during light season and help the public to save energy and labour cost.


Over years the manually operated system has become a problem and people are stranded when there is a project power failure. This is why this work is centered on the design and construction of an automatic electronic generator starting switch. This is fully used in a house that have both NEPA and Generator set. The latest use of field effect transistor (FET) front ends and integrated circuits (IF) channels can scrapp off the use off annual change over during power failure.



This work is limited to the design and construction of an automatic electronic generator starting switch. Some component not available are too obviate this difficulty, several modification were made, where necessary on the circuit diagram.








Automatic electronic generator starting switch has gone a worked transformation from the first mechanically, operated and electrically functioning types to the present day automatic electronically operated types.

The latter has many advantages over the former ones. It is made up of few electronic components and integrated circuit and so is less bulky, hence portable. It is more reliable than those old ones because it is almost hundred percent rust-free, and the problem of clogging either by rust or over heating is completely ruled out.

The mechanically operated type which was operated by turning the shaft through the thread posed a lot of problem and involves labour as in trying to start the generator manually. The electrically operated type use of a rely which was connected such that in the event of power failure, the generator starting switch is connected. In this case, most of the times the relay fail and the system does not function. The present day automatically electronic operated types is highly reliable since it is made to operate any time, it, senses darkness (power failure). The dark sensor is incorporated in the system which senses darkness and allow the operation of the OP AMP which energizes the relay.

The design and construction of an automatic electronic operated generator starting switch have been carried out by a lot engineers in the past. Their design had a lot of short comings which has been corrected in the design. This system is designed to solve the problems of the short-comings encountered in the past designs.



The design and construction of the automatic electronic generator starting switch has undergone a lot of changes from the earlier type to the modern type. The changes started owing to the problem encountered  in the earlier ones. In some areas like the hospital, banks, offices or domestic houses, where power failure may cause a lot damages, the need for a very reliable automatic system is needed.

The mechanical operated type posed a lot of problems as the shaft of the generator has to be rotated mechanically. This earlier systems waste time and causes fatigue most of the time, this system takes time before it is operated. Due to the problems encountered in this mechanically operated type, electrically operated type was designed. This one is operated by the relay terminal connection. In this case, the relay is connected the generator starting coil system. In this type of the system a lot of problem ranges from burning of the relay coil, relay making failure and poor contact making of the relay. These problems encountered in this type, lead to the development of the modern automatic electronic type. This type is designed to arrest all the problems seen in the earlier types. This system has sensor which senses darkness to operate the entire system. The darkness in this case, means the darkness as a result of power failure.



The automatic electronic generator starting switch system consists of mainly electronic components. The components include; 12v step down transformer, rectcying diodes (IN5392), capacitors, regulator, resistors, relay, 12v. 4.5A battery, transistor, sensor (photo-resistor) IC and LED. The mains power supply unit is rectified and filtered for battery charging. Therefore, the output of the regulated power supply unit from the mains is used for charging the only. The power input to the dark sensitive switch is from the battery. The battery supplies 12v to the system. The sensor (photo resistor) senses darkness in the event of power failure making the voltage at the non-inverting input. In this case, there will be output through pin6 to make the relay. In the event of power in the mains supply, the 60w bulb shines on the sensor which reduces the resistance of the sensor. The decrease in resistance allows voltage higher than that at the reference input to enter the IC. This effect will result in no output through the pin6. the lighting of the bulb that shines on the sensor incorportates a delay system. The delay, delays the light for few seconds just to switch on and off the system. For the starting of the generator and switching off the system to disconnect the battery.

The LED which “Comes on” any time there is mains power supply is used to indicate that the system is connected to the generator starting switch. This system is designed to switch on the generator and the system is automatically switched off after the bulb light has gone. The ON and OFF the 60 watts bulb is achieved through RC delay system.






The design and construction of this automatic electronic generator starting switch was done in stages as shown in the diagram below.










Battery supply unit







  1. The Mains Power Supply Unit

The mains power supply unit comprises the 12V step down transformer, the rectifier (diodes), regulator, frittering network and the battery charging circuit. The main operation of the power and supply unit is to maintain power supply to the battery charging circuit when there is power supply from the mains.

The power supply unit supplies a regulated 12V to the battery charging circuit. The configuration of the charging circuit is such that it starts to charge the battery as soon as there is mains power supply.


  1. Battery Supply Unit

the battery supply unit supplies the 12V to the sensor circuit system. The power supply is connected through the relay terminal such that it supplies the system when the sensor senses darkness. The battery supplies constant 12V to the system.


  1. Relay Switching Circuit

The relay switching circuit is used to connect the battery charging circuit when there is power in the mains power supply. The charging circuit is connected from the normally open contact of the relay while the battery is connected the  system through the normally closed contact of the relay.


  1. Sensor Switch Circuit

The sensor switch consists of the light dependent resistor (LDR), operational amplifier (UAAA741), variable resistor, fixed resistor and a transistor (Bc108). The LDR, senses darkness and operates the system by making the IC to give an output. The output is used to operate the relay through the transistor (BC 108). The sensitivity of the system can be varied using the variable resistor.



  1. Output Belay Switching Circuit

This is relay switching circuit which connect the sensor witch to the generator starting system. The relay is connected such that it connects the generator starting circuit through the normally open. In this case, the relay connects the normally open anytime there is output from the IC which eventually connects the generator starting circuit.












Relay switching CCT

  1. The Power Supply Unit

The Power supply unit comprises the battery that is  supplying the system and the mains power supply that is charging the battery when there is power in the mains. The power supply unit also has the charging circuit ie, the circuit that charging the battery.

The power supply unit comprises components such as; 12Volts step down transformer, rectifiers, capacitors, regulator resistors and the battery (12V) that supplies the sensor circuit. The power supply from the battery is connected to the sensor circuit through a 12Volts relay. Also the mains power supply charges the battery through the connection of the relay terminals.






















  1. The Relay Switching Circuit

This relay switching circuit functions as a switch in the system, this circuit connects the power supply unit to the system through the connection of the relay terminals. With 5 terminals. The current capacity is 10A.



  1. The Sensor Circuit

This is the circuit that is sensitive to darkness. The sensor circuit senses darkness and operates the output relay switch.

The sensor circuit comprises, photo resistor (Light dependent resistor, LDR), capacitor, resistors, an operational amplifier, transistor. The complete circuit diagram for the sensor circuit appears in the diagram below.

The operational amplifier ICI is used in a simple trigger circuit. Resistors R2 and R3 provide a reference potential of half the supply voltage to the non-inverting input (f ) pin 3 of ICI, the inverting input ( – ) pin 2, is fed from a potential divider that has preset VRI and resistor R1 as the lower arm and R6, a light dependent resistor (LDR) or photo resistor, as the upper arm.

The light sensor R6, is an ORP12 cadmium sulphide photo – resistor. Its resistance is very high in total darkness, and the minimum dark resistance for the ORP12 is actually one megahm higher light intensity produces reduced resistance, and in very bright conditions the photo resistor exhibits a resistance of 100 ohms.

With the LDR, in a fairly bright condition the voltage fed to the ICI’s inverting input is higher than the reference voltage at the non-inverting input. These result in the output of ICI going low ie no output when the LDR is in dark condition, the resistance is very high such that the voltage at ICI inverting input is lower than the reference voltage at the non-inverting input. This will result in the output of ICI going high, which biases transistor TRI into conduction and switches on relay.

The relay is therefore, switched  off if the detected fight level is above a certain threshold level. The threshold level is controlled using a preset potentiometer VRI, the higher the resistance of VRI/RI, the lower the threshold level.


  1. The Output Relay Switch

the output relay switch connects the generator starting circuit to the 12V battery supply in the event of power failure. In this case, the relay contacts are used in different manner to make it switch one and off.

The relay switching circuit consists of the 12Volts relay, a protecting diode and transistor BC108.













The various component used in the construction of the automatic electronic generator starting switch were built in breadboard first and confirmed in good working conditions. Then they were transferred to the vero-board. Before transferring to vero board, the components Layout were made in graph sheet. The resistor and capacitor were put in place and soldered. Next, were the transistor, IC and the regulator, and the necessary links are made and well soldered. The switches were mounted on the casing. The 12V d.c voltage source was seated in its position in the casing.

After the soldering, the necessary trace – cuttings were made and continuity fast was done to ensure that parts joined together were actually in order.

Then, the casing was built using a portable sized wooden material which brought out the real ideal of the device.

Finally, the device was tested, and it works efficiently.
















Resistor: These are component that offers opposition to the free flow of electric current. It introduces resistor current flow. This resistance is measured in ohms(n) resistor is represented by the following symbols.







There are many types of resistor e.g.

  • Carbon rod
  • Carbon rod with insulated coating
  • Carbon kilm (high stability type)
  • Wired wound
  • Nichroome allogyed e.t.c.

Construction – materials such as geodremium sicular and michrome are for alloys used in the construction of resistors. When wire made of these substance is wound on a tabular ceramic form, the result is a wire wound resistor.

A carbon resistor is produced by mixing a powdered carbon with a binding material like clay and baked into a small hard tubes with the conductor attached to both end other type of resistor are glass or ceramic rod coated with ceramic non-conductive coating with conductor attached at both ends. The value of the resistor dependes mainly on the percentage of carbon in the mixture used.



Some are fixed resistor, wire wound resistor variable type resistor (rheostat) potentiometer adjustable resistor. Theremistor and light Depend Resistor. Some resistor have fixed values while others can be varied either manually eg variable resistor and preset resistor or by heat as in thermestor by light dependent resistor.

The value of resistor many be printed on the body or indicate by colour coding. In colocur coding, there are four bands. The first and second band represents the multiplier of the given colour while mthe fourth band represents the tolerance.

For example in fig. 4.2 below.







The value can be read from the information contain in colour band table as shown below.

Fig. 43 colour       1st Band      2nd Band     3rd Band      4th Band


Brown        1                 1                 0

Red             2                 2                 00

Orange        3                 3                 000

Yellow        4                 4                 0000

Green                   5                 5                 0000

Blue            6                 6                 0000

Violet          7                 7                 0000000

Grey           8                 8                 00000000

White          9                 9                 000000000

Note in the fourth band, which normally has silver, Gold or no colour is the case may be, is given as

Gold 5%

Silver 10%

No colour 20%



From the colour table above, the value of resistor in Fig can read as:

Brown 1

Black 0

Red 00

Gold 10%

Thus the value becomes 1000%, 10% 0r1kn 10%

The tolerance simply means that the value can be 10% less or higher.

WATTAGE: The wattage of low power resistor may usually be determined by the physical size of the resistor, however, high power resistors have their wattage printed on them.



As we have stated earlier that not all resistors have fixed values some are adjustable. The value which, is printed on the variable resistors is the total resistance which, the resistor can offer. The resistance therefore will very between this maximum resistance and zero.











When the knob is turned to zero, the resistance between the terminals is zero while the resistance between 1 and 3 is 100kn. Furthermore, if the terminals of 1 and 3 are connected in the circuit without any interconnection with the terminal 2, it means that the resistor is fixed with the max resistance printed on it. It means that it is no more  that it is no more variable



This is a special type of variable resistor used in this circuit. It works solely on the principle that some materials like cadmium sollphida (Cds) or Cadium Selenide (edse) vary in it resistance when illuminated the amount of variation depends on the intensity of the light or the illuminating object. The symbol is shown in Fig. 2.5






(a) LDR Pictorial

Mode of operation – when light fall on the L.D.R, the resistance acquires energy from the light inform of photons. This energy will dislodge electrons from their parent atom. When these electrons are detached from the their atoms, the conductivity of L.D.R will increase. So it can be seen that the resistance that it resistance is inversely proportional to the light intensity. The response curse of the resistance versus intensity (Lumens) is non-linear but however, over a limited range of intensities a linear approximation curve of LDR is shown in Fig. Below.












The pin type photo device is shown in fig below: Starting from the bottom it consists of a gold electrode a thin V silage a thick D silager, a thin P silager and finally a gold electrode making contact with the PSB. The silicon dioxide is an insulating material. Photons of heat or light passing through the thin P silager strikes atoms in the intrinsic jet and produce free electrons and holes. The electrons moved to positive bias potential.















A capacitor is first two conductors separated by an insulation known as dielectric it stores an electric charge. The capacitor introduces capacitance in the circuit and this capacitance is measured in farads. It is used in power supply circuits to smoothen the ripples in the wave form. Capacitors is extensively used in frequency determining the turning circuits i.e. in determining the time constant of circuits. It can be used in circuits as coupling and decoupling device or by pass there are many type of capacitors.

Paper capacitor.

Mica capacitor

Variable capacitors e.t.c.

It is represented symbolical in fig. 2.8 below:

Fig. 2.8





For the purpose of this circuit, the symbol used above is that of electrolytic type is polarized, that is to say that it has negative and positive terminals. This must be adhered to when connecting it in circuit.






Capacitor                                The Pictorial view of electrolytic






this is an device from semi conductor materials such as silicon and germanium. This device has a PN Junction, which are formed in close proximity within a single crystals of semi-conductor material. It makes use of charge carriers of holes and electron in its conduction. There are two main types of transistor given below.

(1)     Bipolar transistor (BJT)

(2)     Unifolar transistor FET)

For the purpose of this project, the bipolar transistor will be examined because the three transistors used in this circuit are bipolar transistors. The bipolar transistor is two types; they are the NPN and PNP type.


Their symbol is shown in Fig. 3 below.










A bipolar transistor consist of a single carystal of silicon or germanium in which either a thin lager of n – type (the order atom) is sandwiched between two thicker P – type regions or alternatively a thin P – type lager is sandwiched between two n- type regions.  The first configuration whose physical structure is shown diagrammatically in fig (a) is know as PNP, while the second configuration shown in (b) is know as n- p-n transistor. Bath n – p – n and p – n – p transistors can be constructed using four basic methods and hence transistors may be classified as members of one of the four families.

Grown junction, alloy, diffused, or epitaxial transistor.



The transistor are referred to as bipolar junction transistors for the following reasons. ‘Bipolar to signify the transistor has both positive (holes) and negative (electrons) current carriers, both of which play an essential role in the transistors action, ‘Junction’ because the transistor consist of two P – n junction formed close together in a single crystal of semi-conductor. The four basic modes of construction of a transistor is shown diagrammatically in fig (a) and (b).

In summary the light emitting period is formed by diffusing a very thin lager of P – type donors into the surface of the clip and escapes in random direction through its surface as shown in fig (a) above.










A p – n – p epitaxial transistor

An  n – p –n diffuses

A planar transistor







The main use of both P – n – P and n – p – n transistor is an amplifying elements to produce voltage, current, and power gain it can also be used as a switch. Transition common committer, common collector and common base.

It is worthy to note that no matter the mode of connection of a transistor,

  1. The base – emitter junction is forward biased
  2. The base – collector junction is reversed biased.



A relay is an electromagnetic device which can be used as a switch, it can often be activated by a relatively small energy, causing the movable ferzo magnetic core to close or open several pairs.

Our objectives however with respect to this project, is to describe the principle of operation of this device and to show how it can possibly do a mechanical work it is a represented symbolically in fig 4.3   







To show how a relay can do a mechanical work consider the circuit shown in fig. 4.4       








It consist of an exciting coil placed on a fixed ferromagnetic core equipped with a movable called the relay armature. The relay is energized from a voltage source and when this is done the armature is attached to a liver thus closes a second circuit. When no current or very battle current flows through the eleropmagnetic then the attraction or pull on ceases and the control spring pulls back the disk away and thereby opens the controlled circuit.


4.4     DIODES

Diodes are semi-conductor and active electronics device which allows current to flow in one direction only. It is extensively used in power rectification i.e. conversion only. It is extensively used in power rectification i.e. conversion of alternating signal (sigusodial) to steady signal. It is used in radio receivers as detectors. It is also used to protect back amt produced by the relay as applicable in this circuit. There are many types of diodes, they include

Light emitting diode

Power diode

Zener diode

Tumel diode and signal diode.

However, for purpose of this project only the power diode and light emissive diode will be considered. The diode circuit symbol is shown fig. 4.5.







A diode is simply made up of a p – n – junction. This p – n junction is just a single crystal of a very pure semi conductor in which the junction is defined by an interface between a P – and an n – type region. The junction may be formed by separate doping process on either side of the interface or by the over doping of one type of imputing by another in a specified region. The diode is constructed by a growth of a p – type  material or by diffusing n – type impurities into a silicon water or by alloying process. The grown junction diode is shown below in fig. 3.6





Growth of a p – type semi – conductor rod

This  is formed by a growth from a melt of semi- conductor materials. The melt is doped with a controlled amount of acceptor atom impurity for the production of a P – type crystal or donor atom impurity of any n- type crystal is required. A seed crystal is dipped into the melt and slowly withdraw. This crystal act as nucleus for the growth of such large crystal under carefully controlled conditions, rods of p – type and n n type crystals can be grown.

The diffused type; Thus P – N junction is formed by diffusing n type impurities into a silicon water by beating the water to about 12000C and passing the gases containing n – type impurities over the water, the n – type impurities diffuse into the water surface, producing a thin layer of n type semi conductor. This can be cut into internally hundreds of p – n junctions. The diffused type of diode is shown in fig below.






Construction of diode by alloy process in fig below illustrates the formation of a fn – junction by an alloying process. A small pellet of p – type impurity, such as indium or Gallicism is placed on an n – type clip of germanium on silicon. The pallet and clip are then heated so that the pellet melts and alloys itself to the n – type clip. On solidification, the p – type p – layer and a p –n junction within the clip.




Depleted region

P – n junction formed alloying medium it is worthy to note that no matter the mode of  construction used in construction of diode, a p and n- type semi – conductor have been brought to – getter to form a crystalline structure. An ideal diode can only conduct in the  forward bias mode and not in the reverse bias mode. This action can be demonstrated using diagram in figure 4.9







(a) forward biased                                      (b) Reversed biased



This is the type of diode that emits when forward biased. The symbol is shown in fig 4 below.





The light emitting diode (IED) is also known as a sold camp (SSL). It utilizes the fall of an electron from the conduction level of the non- conduction level to produce light and heat; this process is termed spontaneous commission. The led is a semi – conductor junction diode which emits light when current is passed through it in the forward bias conduction. One side of the diode is p – type semi conductor material containing a very large number of holes i.e. covalent bond in the crystal structure have been broke by the removal of one of the pair of electrons forming the bond, while the other side of the diode is an n – type semi conductor containing a large number of free electrons. At zero bias, a deflection zone separates the two regions within all holes electrons having been either recombined or removed. A barrier potential exist across the depletion zone because the recombined holes and electrons have trapped charge at the impurity atom

Site within depletion zone as illustrated in fig 4.7










When energy forward bias voltage is applied to the function to overcome the junction barrier potential, the depletion zone disappears, the hole are free to move across the junction into the p- region where the one impurity carriers. Injected have a very short life time before they meet up. The carriers of opposite change and recombines, and smiths one photo of light which was originally needed to free the electrons for conduction. The intensity of the light emitted depends on the number of the minority carriers available for recombination, which in turn depends directly on the forward conduction current in the diode. The frequency of the light emitted is determined by the energy band gap of the materials used to make the junction. In summary light emitting period is formed by diffusing a very thin layer of p – type through its surface as shown in fig. 4.7 above.



The transformer comprise of a soft union with two inductively compiled could the soft iron core helps to concentrate the magnetic flax generated.







The fig above show the transformer symbol. As mentioned earlier that transformer has two coils which one primary and secondary coil. The primary coil of the transformer usually supply the power, which generates a magnetic flux. The magnetic flux so generated induces voltage into the second coil called the second coil, however, the nature of the induced voltage depends on the member of turns and manner of winding.



There are two basic classes of transformer:

(1)     The voltage transformer

(2)     The current transformer; it is also worthy to note that transformer can be further classify according to the type of coil used. These are either of these transformer designs can be step up or step down transformer.



A transformer is said to be step up when the there is no of secondary coils surpasses the primary coils, thus producing a voltage which is greater than the input voltage.


A transformer is also said to be step down when there number of primary winding surpasses the number of the secondary windings, thus coeading which is lower than the input voltage at the primary.



(1)     Co-efficient coupling: This is equal to the ration of or amount of coupling actually present to the maximum possible coupling invariable does not exceed one.

(2)     An ideal transformer: An ideal transformer is one without any magnetic leakage, in this case the co-efficient of coupling is one for the purpose of the transformer used in the power supply of this project. Let us examine an ideal transformer in details and from there we can derive the transformer equation.

As first approximation to a quantitative theory consider a transformer with a primary winding OF NI turns and a secondary winding of N2 turn a shown in f 4.3 below.

Assuming that the resistance is negliable and the permeability of the core is so high that only a neglible exciting current is required to establish the flux. When a periodic voltage VI is applied to the p windings and a core flux must be established such that the counter EMF, equals the applied voltage provided that the winding resistance is negligible that the winding resistance is negligible thus:

Vi – el = N1 df/dl- – – – (1)

The core flux also links  the secondary and produces an induced emf e2 and an equal secondary terminal voltage. Voltage v2 given by v2 e2 = N2 df/dt – – (2)

From equation one

V1 NI df/dt

VI df/dt – – (3)

The substituting for equation 2

V2 N2df/dt

V2 = N2V1


V1N2 – V2N1


V1/V2 = N1


Thus it can be concluded that an ideal transformer changes voltages in the direct ratio of the turns in its windings. Furthermore, the instantaneous power input equals instantaneous power output, a necessary conditon because all causes of active and reactive power output, a necessary condition because all causes of active and reactive power losses in the transformer have been neglected

VI 11 = V2 12 – – (5)

V1/V2  12/11  – – (6)

Also ampere turns at the primary equals ampere turns at the secondary.

N111 = N212 – – (7)

11/12  = N2/N1 – – (8)

V1 =  N1  = 12  – –    (9)

V2     N2     11




Thus equations (9) gives the transformer equation.






















I constructed this circuit and it works perfectly. However the modification suggested above are in line with the electronics principles and would be very interesting if the up coming students will employ any of these modification in their future projects. I am very optimistic that they will be successful.













Mel Sladdin (1998): Electronics MC Grawhill Book Co.Codon Pg. 210.


Paul B. Zbar (1989): Industrial Electronics a Text O.A Lab Mannual (Fourth Edith) Pg. 225 – 228.


Angelo, E.J., (1987): Electronic Circuit 2nd Edition MC Gravhill Book London. Pg. 210.


Benard, G., (1989): Application of Electronics MCGravhill Book Co. London Pg. 225 – 228.


M.P. Horsey, (1999): Electronics in Practice Pg. 220 – 230.


R.G. Meadows, (1987): Technician Electronics II Pg. 200 – 210.











  • Switch
  • 12V Step down transform
  • Rectifying diodes (in5392)
  • 2200uf (250 capacitor)
  • Capacitor (103)
  • Voltage regulator (7812)
  • Capacitor (470uf – 1250)
  • 12V Relay
  • LED (light emitting diode)
  • Transistor (LM 317)
  • Resistors
  • Rechargeable battery 12V.
  • LDR (light dependent resistor)
  • IC UA741
  • Transistor BC108

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Raw African Yam bean (Sphenostylis stenocarpa) was subjected to various processing methods Viz: steeping in water for 6 hr and then boiling for 10, 20, 30, minutes respectively (samples B); steeping in water for 12 hours and then boiling for 10, 20, 30, minutes respectively (sample C) and finally sample A was raw yam bean which served as control.  The entire sample was dry – milled into fine flours. The glycosidic cyanide, crude protein, ash, moisture, some functional properties and bulk density of the flours were analyzed from the results, protein and cyanide content of sample A (raw sample) are 25.20% and 72.23ml. results showed that the toasting, process gave the highest protein (24.12) with no trace of cyanide and it negatively affected the protein content of the samples reducing it from 25.20 to 17.57, 17.51(%) respectively. 12 hours soaking and few minutes boiling process negatively affected the protein content of the samples reducing it from 25.20% to 13.12, 12.78, 12.09 (%) respectively but have the strongest impact in covering the cyanide level from 72.23ml to zero respectively. Moisture content ranges from 400% – 14%, Ash ranges from 2.50% to 5.00%, water absorption ranges from 105g/ml to 290g/ml, oil absorption ranges form 0.98 – 1.95g/m. The bulk density showed 0.74g/ml – 0.88g/ml.












  • Literature Review

2.1     Legumes

  • Nutritive Value Of Legumes
  • African Yam Bean
  • Utilization Of African Yam Bean
  • Limitations In The Utilization Of African Yam Bean
    • Unacceptable Flavour
    • Hard – To – Cook Phenomenon
    • The Presence Of Anti – Nutritional Factors
    • Pre – Conditioning Treatment Used In African Yam Bean Processing

2.7.0           Functionality of Legume Protein/Flour

  • Nitrogen Solubility
  • Water And Oil Absorption
  • Emulsion Capacity
  • Foam Capacity
  • Gelation



3.0     Materials And Source

  • Sample Preparation
  • Flow Charts For The Production Of The Different flour samples
    • Flow Chart For The Production Of Sample A (Raw Sample)
    • Flow Chart For The Production Of Samples B
    • Flow Chart For The Production Of Samples C
    • Flow Chart For The Production Of Toasted Sample (D Sample)
  • Determination Of Functional Properties Of African Yambean Flour
    • Water Absorption Capacity
    • Oil Absorption Capacity
  • Chemical Composition Of African Yam Bean
    • Determination Of Moisture Content
    • Determination Of Ash Content
    • Determination Of Crude Protein Content
  • Determination Of Glycosidic Cyanide
  • Determination Of Bulk Density



Results / Discussion


Conclusion and recommendation




African yam bean (Sphenostylis stenocarpa) belongs to the genera papilliona sec which is in the class known as Leguminousae (Okigbo, 1973). It is one of the neglected indigenous grain legumes in Nigeria. It is produced mostly in the eastern part of the country where it is consumed in different forms such as snacks, delicacy, man meal etc. It can be used for the fortification of other foods (Eke, 1997)

In Nigeria, it has as many names as there are communities cultivating it. Some of the names are Okpdudu, Azam, Uzuaku, Ijiriji, Azara, Ahaja, Nzamiri, Odudu, Girigiri (Hausa), sese (Yoruba) and Nsana (Ibibio) (Ogbo, 2002).

The high protein content of African yam bean makes it an important source of protein in the diets of population groups of many tropical countries (Kon, 1979, Ekpen young and Borchers, 1980). In addition, the high protein bean flour fractions could be substituted for wheat flour to produce acceptable qualities of cookies breads and leavened doughs (Uebersax and Zabik, 1986; Nzereogu, 1993).

It may also be consumed as porridge after cooking. The mature dry seeds can be used to prepare “moi – moi” and “akara” (Ezueh, 1973; Akoma, 1996). The African yam bean apart from being rich in protein also contains carbohydrate, fat and minerals (NAS, 1979).

A major constraint in the utilization of African yam bean is the different dehulling method. Traditionally, the dehulling method involves manual removal of the hulls from the individual soaked seeds. This method is quite laborous (labour intensive), time – consuming and does not favour effective utilization of the bean. It is widely believed that under cooked African yam bean seeds cause diarrhoea and over cooked seeds cause constipation (Asusu and Undie, 1986).

Previous works showed that steeping will among other things improve the dehulling characteristic of the African yam bean while maintaining the nutritional quality viz: invitro protein digestibility and also improving the functional properties when processed into flour (Abbey and Berezi, 1988). It is evident that better processing methods will not only enhance the acceptability and utilization of this legume but will also improve the nutritional status of the consuming populace (Uebersax et al, 1989).

The overall objective of this study is to investigate the various processing methods and their effects on the protein and cyanide content of African yam bean in conclusion, before the commencement of any research or project, there is meant to be aim/aims of such research.

As such, the aims of this study include:-

  1. To determine the hydrogen cyanide content of the flour.
  2. To analyse for the crude protein content of the flour.
  3. To determine some of the functional properties of the flour.
  4. Determination of the chemical composition of the flour.
  5. To determine the bulk density of the flour.










2.1     LEGUMES

          Food legumes are classified into two viz: the pulse and oil seeds. The pulses are those species of legumes harvested traditionally for their mature seeds and are major sources of dietary proteins and calories in food and feed products throughout the world (Ihekoronye and Ngoddy, 1985). Examples of pulse legumes include pigeon pea, cowpea, and chick pea while the oil seeds consist of those legumes uded primarily for their oil content which may be extracted by pressing or by solvent extraction. These include groundnuts and soybeans (Ihekoronye and Ngoddy, 1985).

The pulse legumes are also rich in digestible carbohydrate mainly starch and concentrations of 50% or more are common. Legume seeds rich in carbohydrate are noted t o contain relatively small amounts of lipids mainly as phopholipids (Duke et al; 1979). When consumed, they lower serum cholesterol level and this probably may be related to the high soluble storage polysaccharide contained in the seeds (Anderson et at; 1984).

Some legumes apart from being rich in proteins and carbohydrates, are also good sources of lipids, dietary fibbers, vitamins and mineral (Duke et at; 1979). The fat content of legumes is less than 3% with exception of some like groundnuts and soybeans and naturally contains an appreciable level of water (Ihekorony and Ngoddy, 1985). Legumes are also known to contain ant-nutritional factors such as lectin, saponine, phytin and trypsin inhibitors (Eneobony et al; 1996).



The legume seeds are second only to the cereals as sources of human food and provide the much needed protein to our predominantly vegetarian population (Giami et al; `992). Legumes contain 17 to 30% protein in a dry basis which is nearly twice or thrice the value found in cereals and 20 times that of cassava with soybean having as high as 42% protein (Giami et al; 1992). Legumes are good sources of lysine, tryptophan and threonine but are low in the sulphur containing amino – acids – metthionine, cystine and cystein (Evans and boulter, 1974).

In addition to protein content, legumes contain upto 60% carbohydrate mainly in the form of starch granules – amylase and amylopectin. While sucrose is the major sugar in legumes (Ihekoronye and Ngoddy, 1985). The fat content of most legumes range from 1 – 2% with oleic and linoleic acids being the main unsaturated fats and oils while palmitic acids are saturated (Deboland et al; 1975).

Deboland et al; (1975) also reported that legumes contain reasonable amount of macin and riboflavin which are ten times and five times respectively, more than those of most cereals and with some amounts of carotene. The sprouted seeds were found to be good source of ascorbic acid.

The proximate composition of some common legumes are shown in Table 1

Table 1:

Common Legumes and their Proximate Composition













Cowpea 11.5 22.7 1.6 61.0 4.2 3.2
Groundnut 7.3 23.4 45.3 21.6 2.1 2.4
Lima bean 10.5 19.8 1.3 65.4 nd 4.0
Peas 13.6 22.2 1.4 60.1 6.0 2.0
Pigeon peas 11.5 20.4 1.2 63.4 4.4 3.5
Soy bean 10.2 35.1 17.7 32.0 4.2 5.0
Winged bean 9.7 32.8 17.0 36.5 nd 4.0


  • per 100g edible portion of dried mature wholeseeds.

nd Þ not determined


  • AFRICAN YAMBEAN (Sphenostylis Stenocarp)

The African yam bean is a member of the family papilona cean which is part of the family known as the Legumino sac (Okigbo, 1973). It is a perennial herbaceous plant, treated mostly as an annual crop. It is cultivated for its edible seeds tuberous roots (Duke et al; 1979). The plant is a vigorous vine that two twins and climbs to height of about 3m and requires staking. The duration of the crop cycle is 150 – 300 days. The ripe pods vary in length between 120mm and 300mm and contain 10 to 30 seeds. According to Duke et al (1979), the average yield per hectare is 300 – 500kg of dried seeds whereas the average yield of tubers is close to 2 tones per hectare.

African yam bean is strong climber with a tuberous rather spindle – shaped root and having 3 ovate – acuminated leaflets. The flowers are pale with deeper purple or pink centres on long axillary stalks. The fruits are linear, speckled or marbled from brown to while with seeds (Akoma, 1996)

The proximate composition of raw African yambean according to Ene-obony, (1996) is as follows moisture 10.6% (wet basis), protein – 19.5%, carbohydrate – 62.2% fat 2.5% and ash 2.8%. the seeds are rich in minerals such as K,P, mg, Ca, fe and zn but low in Na and Cu. African yambean is cultivated with yam (hence the name yambean), mainly between the months of may and July (Ogbo, 2002).

Ecologically, yam bean is found in grass land, wood grass land but sometimes in marshy places. It   grows well on range of soil not necessarily producing the best on rich garden soil (Eke, 1997). Eke and Akobundu (1993) investigated the functional properties of African yam bean seed flour and reported that these vary under different processing conditions. Steeping was found to among other things generally improve the absorption properties of the flour.

Below in table 2, is the chemical composition of African yam bean.



Chemical Composition of Yambean.

Aspartic Acid


Glutaminic Acid






























Source: FAO (1974)



Just like other legumes, African yambean can be prepared into food. In Nigeria, it is cultivated for its seeds with just a report of the tubers being used as food as well (Ezueh, 1973). The seeds are eaten on their own with palm oil and spics or mixed with other foods such as maize or yam. It can be consumed as a porridge after long time cooking (Akoma, 1996).

The mature dried seeds according to Enwere et al; (1990) may be toasted in fire and while still hot they are split with the use of pestle, winnowed and eaten as snack along with palm-kernel or coconut. They can be soaked for many hours, after which the seed coats are removed, the seeds are then ground into a paste to which palm oil, pepper and other condiments may be added to taste. From this, it can be made into moi-moi (steamed paste) or akara (fried paste) (Enwere et al; 1990).

Okwamba (1990) noted that African yam bean seeds can be processed into flour and this flour can be substituted for wheat flour at 20% level in the production of cake, bread and biscuits. He further stated that the flour can also be used in the fortification of “Ogi” for weaning.

One of the     most limiting factors in the utilization of most legumes is their objectionable “beany” flavour (Kalu, 1992) African yam bean seed when roasted has such characteristic flavour and texture during mastication. Kalu (1992) also reported that these flavours can be developed by the lipoxy genase activity or oxidative rancidity in the raw crushed bean prior to their use. This “off-flavour” affects consumer’s acceptability.

For increased acceptability of most legume products, it is necessary to ensure a reduction to some extent if not entirely the development of objectionable flavour in these products. The beany off – flavour of the seeds can be reduced by soaking seeds in PH below 3.8% prior to processing into flour (Kalu, 1992).

2.5.2  Hard – to – cook Phenomenon

Hard – to – cook is another problem associated with the consumption of African yambean. As the storage period of this legume increases, there is tendency for seeds to develop the hard – to – cook phenomenon (Nzereogu, 1993).  Njoku et al (1989) reported that the seeds of African yam bean require a long cooking time because of t e hard testa which form a barrier to rapid imbibitions of water. It has been shown that pre – soaking of legume seeds in water or salt solutions reduce the cooking time considerably.


2.5.3  The Presence of Anti – Nutritional Factors

The hulls of this legume are known to contain trypsin inhibitors, lectins and flatulent factors which can variously interfer with the biological utilization of the nutrients contained in the seeds. African yam bean as a legume also contains Oilgosaccharides including raffinose and starch those which are responsible for flatulence (Eke, 1997).





Processing, a food product storage and quality enhancer may include water cooking, soaking, germination and sprouting, delulling and roasting (Uebersax et al; 1989).

Water Cooking

Cooking of legume seeds is a thermal process which provides tenderization of the cotyledon. It also increases the product palatability and helps to inactiviae endogenous toxic factors that would remarkedly limit the final nutritional value (Uebersax et al; 1984).


Soaking of the seeds may be used to moisten and soften the seeds to reduce cooking time or aid in seed – coat removal. Soaking also reduces the toxin content and surface contamination. (Anderson et al; 1984).

Germination / Sprouting

Soaking legume seeds and holding at ambient temperatures will facilitate germination (FAO, 1982). Germination has profound effects on the physio – chemical composition changes in dry beans and improves the nutritional quality of legumes by increasing vitamins such as ascorbic acid, riboflavin, choline, tocopherol and pantothenic acid. The sprouted grain may be consumed fresh or if followed by seed coat removal can be roasted or ground for use in soups or side dishes (Uebersax et al; 1984).

Dehulling and Roasting  

Dehulling and splitting the cotyledons reduces cooking time considerably. In large – scale dry dehulling method, oil is mixed with the seeds by passing through emery – coated rollers to abrade the surface. This is common practices for legumes with particularly tough seed coats. African yam bean seeds are difficult to dehull. This as affected the extensive use of the crop. The seed coats are tightly bound to t he cotyledon thus hardly remove without additional treatments such as steeping, malting ad roasting (Enwere et al; 1990).

The hulls of his legumes a re known to contain  trypsin, inibitors, lections and  flatulent factors which can variously interfer with the biological utilization of the nutrients contained in the seeds (Eke, 1997). Dehulling should be encouraged as it decreases the level of starchyose and other flatulent factors and render conizable dietary iron unavailable to the body (Ogun et al; 1989).

Ene – Obony and Obizoba (1996) also report that dehulling reduced the tannin content cont had no significant effect on phytate and invitro protein digestibility of African yam bean except fro seeds soaked for 12 hours before dehulling.



Functional properties are intrinsic physicochemical characteristics which affect the behaviour of proteins in food systems during processing, manufacture, storage and preparation (Giami et al; 1992). These include nitrogen solubility water and oil absorption capacity, foam capacity and gelatin functional properties of protein flours depend on characteristics indigenous to the kernels and on conditions to which the kernels have been subjected during processing (Akoma, 1996).



Protein solubility is an index of functionality and potential application in food products solubility characteristics are influenced by factors such as origin, processing conditions, PH, iron strength and the presence of other ingredients (Kinsella, 1979).

Deboland et al; (1975) reported tat solubility of proteins can be reduced by heat treatment. A plot by Narayana and Rao (1982) between nitrogen solubility versus PH of winged bean flour showed only one minimum 23% around PH 4.5. They also showed that soyabean meal has minimum nitrogen solubility of 10% around PH 4.5 and a maximum of 9.5% at PH 10.0. Deboland et al; (1975) also showed that low sodium chloride concentration enhanced protein solubility where as high concentration decreases nitrogen solubility.



Water absorption characteristics represent the ability of a product associate with water under conditions where water is limiting. For example in doughs and pastes. Proteins are capable of binding large quantities of water due to their ability to form hydrogen bonds between water molecules and polar groups on the polypeptide chain (Giami et al; 1982). Water absorption capacity from work done by Nereogu (1993) enables bakers to add more water to dough and so improve handling characteristics and maintain bread freshness.

Likewise, oil absorption refers to the physical entrapment of oil by protein. The protein’s oil absorption can be defined by the volume of oil absorbed after centrifugation (Kin Sella, 1997). Heat processing has been shown to increase the water and oil absorption capacities and this was attributed to the heat dissociation of proteins, gelatinization of carbohydrate in the flour and swelling of crude fiber (Narayana and Rao, 1982).



An emulsion is formed when oil is mixed with water by shaking and the two is dispersed in each other. The quantity of proteins strongly influences their potential to form oil – in – water emulsion (Akoma, 1996). Changes in the emulsion capacity of lours can be influenced mostly by PH adjustment and associated changes in   protein solubility. This is as a  result that emulsion capacity of soluble proteins depends on hydrophilic and lipophillic proteins (Kinsella, 1979).

Kinsella (1979) laso reported that an increase I n polar group would increase the hydrephilicity of proteins. An alteration in molecular configuration would expose the interior hydrophobic or lipophillic groups to the aqueous phase. Liquid retention is an index of the ability of protein to absorb and retain water or oil which in turn influences the texture and mouth feel of foods (Okezie and Bello, 1988).



Foam formation and stability is a surface active function of proteins. A colloidal system wcih forms by incorporation of air (gas) into a soluble surface active agent is foam (Kinsella, 1979). He went further to explain protein denaturation which aids foam formation by unfolding of protein molecules.

Some factors which may influence foaming properties include protein source, method of preparation, solubility, concentration, PH, presence of salt (Narayana and Rao; 1982).

A remarkable colloidat system in which large volumes of liquids are immobilized by small amounts of solid materials, the liquid consisting the dispersed phase is a gel (Eke, 1997). The variation in the gelling properties of different legume flours is associated with the relative ratio of different constituents – proteins, carbohydrates and lipids that make up the legumes which suggests that interactions between such components may also have significant role in their functional properties (Narayana and Rao, 1982) have studied the significance of gel forming ability of legumes such as soybean protein. Their report showed that soybean protein dispersion forms a gel  upon heating and cooling, and upon dialysis following alkali treatment.
















The dry seeds of African yam bean (Sphenostylis Stenocarpa) were purchased from Ogbete main market in Enugu North Local Government area of Enugu State, Nigeria.



The seeds were cleaned and sorted to remove stones, contaminants and unwholesome ones. The seeds were divided into four portions for the work.

The first portion was treated as the raw unboiled milled sampled and was labeled as sample A.

The second portion was steeped in potable water for 6 hours at room temperature, dehulled manually and was divided into four parts. The part was oven – dried at 600C without boiling, milled and sieved into flour. This was labeled as sample B. The remaining three parts were boiled for 10, 20, 30 minutes, over – dried at 60OC, milled and sieved into flour. These were labeled as B1, B2, B4 respectively.

The third portion was steeped in potable water for 12 hours at room temperature (28 = 2 OC), dehuylled manually and was divided into four parts. The first part was oven – dried at 60OC without boiling, milled and sieved into flour. This was labeled as sample C. The remaining three parts were boiled for 10, 20 and 30 minutes, oven – dried at 60OC, milled and sieved into flour. These were labeled as C1, C2, & C3 respectively.

The fourth portion was toasted, dehulled, milled and sieved into flour. This was labeled as sample D. The milled samples were stored in dry air tight plastic containers appropriately labeled until required for analysis.




(African Yam bean Seeds)









fig 1:           Flow chart for the production sample A. (raw sample).



Steeping (6 hours )

Dehulling              testa


BO = Boiled for 0 min

B1 = Boiled for 10 min

B2 = Boiled for 20 min

B3 = Boiled for 30 min


Oven – drying




fig 2: Flow chart for the production of sample B.


  • (African yam bean seeds)


Steeping (12 hours)


CO = Boiled for 0 min

C1 = Boiled for 10 min

C2 = Boiled for 20 min

C3 = Boiled for 30 min

          Dehulling             testa


Oven drying (60OC)




fig 3: flow chart for the production of sample C





dehulling            testa




fig. 4: Flow Chart for the Production of Toasted Sample.






The method of Odo and Ishiwu (1999) was used. 2g of the flour was weighted a into test tube of distilled water was measured and the flour stirred with water until a dough of a given consistency was achieved. It was centrifuge for 5 minutes at 2000 r.p.m. The volume of water used was noted. This was expressed as percentage of the weight of the flour used.


% water absorption       =                 Quality of

H20 absorbed C 100

Weight of                 1



The method of Odo and Ishiwu (1999) was used. 1g of the flour was weighted into a test tube. 10ml of groundnut oil was measured and the flour stirred with oil until dough of a given consistency was achieved. The mixture was heated in a boiling water bath for 30 minutes. The heated tubes were cooled to room temperature under running water and were centrifuged for 5 minutes.

The weight of the sample sediment was recorded and the oil absorption capacity expressed as gram of oil absorbed per gram of flour was calculated using the expression.

OA (W/W)            =       Ws (g)         –        Wf (g)


OA    =       oil absorption capacity (g/g)

WS    =       weight of sample sediment (g)

WF    =       weight of sample flour (g)






The hot oven method as desecrates by Odo and Ishiwu (1999) was used. Ten petridishes were thoroughly washed, dried in the oven at 100OC for 30 minutes cooled inside a desiccator and their weights determined in a weighing balance 2g of the samples were placed in each petri dish and the petri dishes placed inside the oven at 100oc for 1 hour, after which they were removed, cooled in a desiccator and weighted. They were placed back into the oven and dried for further 30 minutes, cooled and weighted.

The drying was continued and weighted repeatedly until a constant weight was obtained. The percentage moisture content was calculated from the weight loss of the sample.

% Moisture content                 =

Weight of dish      –        weight of dish

+ Sample                       + sample after        C    100

                                      Drying                              1

Weight of sample



Ash determination was carried out as described by Odo and Ishiwu (1999). Ten crusibes were washed thoroughly, dried in hot oven at 100oc, cooled in a desiccator and weighted. 2g of the flour sample was weighted into the crusibles and put in the furnace. They were heated gradually until a temperature of 600oc was reached.

This temperature was maintained for 6 hours. After ashing, the furnace was switched off and the temperature was allowed to drop before the crusibles were removed. The crusibles were then put inside a desiccator to get cooled after which they were weighted and the percentage ash was then calculated as:

% Ash         =       W – Z         C     100

                                N                         1


W      =       weight of crusible + ash

Z       =       weight of empty crusible

N       =       weight of the sample




The microkjeldahl method of crude protein determination as was described by pearson (1976) was used.


1g of minced sample was placed inside 100ml digestion flask and 2g anhydrous sodium sulphate, 1g hydrated cupric sulphate, a pinch of selenium powder, 10ml concentrated sulphuric acid was added into the flask. The flask was placed on an electric coil heater and gently boiled at first until blacking occurred; heating was continued until the solution became clear. The flask was allowed to cool. Distilled water was then introduced into the flask upto the 100ml mark. The flask was then thoroughly shakened.



Steam was passed through the microkjeldahl distillation apparatus for 10min, 5ml of boric acid was placed in 250ml conical flask and 2 drops of the indicator added. The conical flask was placed under the condenser and 5ml of the diluted digest placed in the distillation apparatus and was rinsed down with distilled water.

The cup was closed with the rod and 5ml of 40% NaOH was put in. this was let in carefulling leaving behind a little to prevent ammonia escaping. Steam was then let through for about 5min, until the amount of liquid in the conical flask was about twice what it was in the beginning of distillation. The boric acid indicator was titrated with O.o1m HCL to the end point, which was pinkish in colour. The titre volume was recorded, ie volume of 0.0lm HCL that changed the indictor from green to pinkish colour. Percentage crude protein was calculated thus:

% Crude protein   =       0.0001401

                                                X titre X 6.25

X 100

      5                        C   100

                                                Weight of sample   1




The method described by FAO (1984) was used. Approximately 10g of the flour sample was transferred to the I litre distillation flask. 200ml of distilled water was added and 10ml of or thophosphoric acid was also added. It was stoppered hermitically, mixed well and was left in the flask for 12 hours in an incubator at 38oc.

The flask was fixed to the distillation apparatus and was distilled into 20ml water containing 0.5g NaOH. 100ml of the distillate was collected transferred to a 250ml volumetric flask and was made up with distilled water from this flask, 100ml was pipetted into a beaker and 2ml of potassium 10dide solution and 1ml of ammonia solution were added.

This was titrated with silver nitrate solution until permanent turb— appeared. A black background was used for easy recognition of the end point. A second titration was made with another 100ml portion of the distillate and the mean of the two titration was taken. Double determination was carried out on the same sample and a blank test was also carried out under the same conditions as in the determination but the distillate was replaced with distilled water.




Under the conditions of the reacting 1ml of 0.0/N silver nitrate solution corresponds to 0.54mg of hydrocyanic acid (NCN). The content of glyco sidic hydrocyanic acid, expressed in milligrams of HCN per 100g of sample was calculated as:

0.54 (V0 – V1)  X  250  100          =       135 (V0 – V1)

100           m                            m


M      =       The mass in gram of the test portion.

V0      =       The volume in ml of 0.01N silver nitrate solution used for the determination

V1      =       The volume in ml of 0.1N silver nitrate solution used for the blank test.


INTERPRETATION:  If the amount of HCN determined is less than 1ml of titrant volume, the smaple is considered free from glycosidic cyanide.




This was done by using the method of Pearson (1976). 20g of flour sample were placed in 100ml measuring cylinder and then the cylinder was tapped gently to a constant volume. The bulk density was measured in glml by expressing the true volume of the flour sample. All measured in triplicates.

Bulk density         =       weight of sample

Volume of sample

After tapping















Sample A

Sample B

Sample B1

Sample B2

Sample B3

Sample C

Sample C1

Sample C2

Sample C3

Sample D



































Sample A

Sample B

Sample B1

Sample B2

Sample B3

Sample C

Sample C1

Sample C2

Sample C3

Sample D
























  BULK DENSITY (g) (ml)
Sample A

Sample B

Sample B1

Sample B2

Sample B3

Sample C

Sample C1

Sample C2

Sample C3

Sample D













Sample A


Sample B

Sample B1

Sample B2

Sample B3

Sample C

Sample C1

Sample C2

Sample C3


Raw sample

Steeping boiling



6 hr

6 hr

6 hr

12 hr

12 hr

12 hr

12 hr




0 min

10 min

20 min

30 min

0 min

10 min

20 min

30 min










Sample D Toasted Sample    


Presented in table 1 is the chemical composition of the samples which include the moisture content, Ash and protein content. The data for moisture, Ash and protein content as obtained in this study is consistent with studies on previous works done by Ene-Obony, (1996). From the table, the results were fluctuating due to the processing methods used.

For the moisture content, sample A which served as control gave the highest value implying that the moisture was still infact probably because it was not subject to any drying and heating processing for the ash content, the control sample has the highest percentage whereas the sample made form 12 hrs soaking and 30 minutes boiling has the least. These results were dependent on the processing methods.

Table 1 also reveals the protein content of the various flour samples. The table shows that the control sample has the highest percentage of protein and that there is a decrease in the protein content of the soaked and boiled samples. This result was compared with the work done by Ene-Obony and Obizoba (1996) which reported that dehulling reduced the tannin content but had no significant effect on phytate and invitro protein digestibility of African yam bean except for seeds soaked for several hours before dehulling.

Table 2 reveals some of the functional properties carried out on the samples. This table shows that toasting method (sample D) has the least water absorption capacity when compared to other processing methods. This then implies that flour made from toasting will not be ideal in the production of dough and pastes. Since water absorption capacity from work done by Nzereogu (1993) enables bakers to add more water to dough and so improve handling characteristic and maintain bread freshness. Presented in table 3 is the bulk density of the samples. From the result, the toasted sample has the highest bulk density when compared to other processing methods.

From Table 4, total cyanide for the raw sample which served as control was 72.23ml. However Edem et al (1990) working with one variety of African yam bean recorded 61mg/g on a dry weight basis. It would be difficult to compare this value with my result since the authors did not identify the types of African yam bean used in there study. As recorded in table 3, 12 hrs soaking and then boiling and the toasting method reduced the cyanide content of the samples to zero. For instance Anderson et al; (1984) recorded a 95% reduction in cyanide content of one variety of African yam beans after soaking for several hours.

Conclusively, the work had shown that dry heat substantially reduces or eliminates gycosidic cyanide in African yam, bean with little or no damage on the nutrients but has a poor water absorption capacity effect on the flour sample. But on the contrary, 12 hrs steeping also reduces or eliminates the cyanide but causes nutrient losses and has a high water absorption capacity effect on the flour samples. Therefore, a careful control of the processing condition is important to prevent both functional and nutritional damage to the various nutrients. But whereby this cannot be achieved 12 hrs steeping could be adopted but the flour can be fortified after processing to make up for the lost nutrients.









From the work done, 12 hrs soaking an few minutes boiling tends to be the ideal processing method for this legume. This is because this processing method eliminated the cyanide content and the flour samples have high water and oil absorption capacity which is needed in dough and pastries production. The only problem faced with this processing method was nutrient losses – which can be made by fortification of the flour after processing similarly, development of new genetic varieties with minimum level of these legume based toxicant should be encouraged.

Such a step would fully complement efforts aimed at substituting wheat flour with flour made from tropical crops e.g. African yam bean flour. Since wheat cannot be grown in humid tropical areas, supplies must be imported necessitating expenditure of foreign currency which is often very scarce.

Therefore from the results gotten from this study, I now suggest that wheat flour could be substituted with African yam bean flour in the production of bread, cookies, pastures etc because apart form nutritional enhancement, it could save a good deal of foreign exchange for our country Nigeria.



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of African yam bean flour as affected by processing. J. food chem. 48: 340.

Enwere, N.J. Hung, Y.C. and Ngoddy, P.O. (1990). Texture and

micro structure of African yam bean (Sphenostylis Stenocarpa) products in food of plant origin. Afro – orbis, publications, Nsukka. P. 61.


Evans, I.M. and Boutler, D. (1974). Amino acid composition of

seed meals of yam bean (Sphenostylis Stenocarpa) and lima bean (phaseohis luna tus) J. Sci. Food and  Agric. 25(8): 919 – 922.

Ezueh, M.I. (1973). Cultivation and utilization of minor food

legumes in Nigeria. Tropical Grain Legume Bulletin 28.

F.A.O. (1986). Manuals of food quality control. Food Analysis:

quality, adulteration and tests of identity. F.A.O. Publication Rome. 14.

F.A.O. (1982). Tabulated information on tropical and sub –

tropical grain legume. Plant production and protection division F.A.O. Publication. Rome. 9.

Giami, S.Y., Bekebain, D.A. and Gemlike, N.J.T. (1992).

Proximate composition and functional properties of winged bean (Psophocarpus tetragonocobus). Nig. J. Nutrition Sci. 13:36 – 38.

Ihekoronye, A.I. and Ngoddy, P.O. (1985). Integrated Food

Science and Technology for the Tropics. Macmillian Pub. London. Enugu. Pp. 38 – 90

Kalu, E.N. (1992). Control of beany off – flavour in African

yam bean flour and paste by acidification. B. Tech Thesis. Federal University of Technology Owerri, Nigeria.

Kinsella, J.E. (1979). Functional properties of soy protein J.

American oil chem. Society. 56: 242 – 258.

Kon, S. (1979). Effect of soaking temperature on cooking and

nutritional quality of beans. J. Food Sci. 44: 1329 – 1331.

Narayana, K. and Rao, M.N.S. (1982). Functional properties of

raw and heat processed winged bean (Psophocarpus tetragonolobus) flour. J. Food Sci. 47: 1534


NAS (1979). Tropical legumes: Resources for the future.

National Academy of Science (NAS), Washington D.C. pp. 27 – 29.

Njoku, H.O, Eli, I. And Ofuya, C.O. (1989). Effect of pre –

treatment on the cooking time of the African yam bean (Sphenostylis Stenocarpa). J. Food Sci. 54:758

Nzereogu, H.N. (1993). Production and evaluation of yam bean

and bambara groundnut (Voandzeia susterranea L). J. Sci Food Agric. 41: 123 – 124

Odo, F.O. and Ishiwu, C.N. (1999). Experimental Procedures

for Food and Water Analysis. Computer Edge Pub. Enugu pp. 38 – 90.

Ogbo, A.I (2002). Nutritional Values of some Tropical Food

with Allergy/Toxicants. Computer Edge Publishers. Enugu. Pp. 73 – 75


Ogun, P.O., Markakis, P and Chenoweth on certain anti-

nutrient in cowpea (Vigina Ungniculata). J. Food Sci. 54(4): 1085.

Okezie, B.O. and Bello, A.B. (1988). Physico Chemical and

functional properties of winged bean flour and isolate compared with soy isolated J. Food Sci. 53 : 450 – 454.

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Stenocarpa) harms. First grain Legume Improvement Workshop. 29 October – 2 November. Ibadan

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yam bean (Sphenostylis Stenocarpa) flour on the organoleptic properties of ogi. B. Tech. Thesis Department of Food Sci and Technology Federal University of Technology, Owerri.

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Lusas, E.W. (1984). Mineral and Phytic acid partitioning among air classified bean flour fractions. J. Food Sci. 49:569.





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Elements of Printing

Method of Identification

Difficulties in Letter Press Printing

The monotype


Hot metal


Letter Press Machine

Camera Work


Computer operation

Components of a Computer System


The Printing Ink

Fountain Solution

Printing Paper

Off set Machine Printing

Principle of Offset Litho












Between 15th century from the invention of muturable types in the 15th century to the years 1800 the techniques of cover posing printing and book binding am ong the only existing processes of the period noticed a — improvement revision of techniques and equipment were few and of modest conception what printing look like before 1683 started in African, Egypt to be precise with writing on heaves found on the back of the Rive Nile on these leaves called papers were written massages and attached to dogs and pigeons to derived destinations we said above then what printing was like is not known and thin back. In 16 83 Joseph Moxon’s monomental work was God fired and for the first time printing procedure was codified.


Early methods and their investors

We have —- where we and erpert opinion suggestions that gutenburg modelled him — press on proelum or wine press. As time elapsed so refinements were made to big and clumsy presses of 15th century, the TUMPAN AND FRISKET were added in about 1545 and the metal series was introduced in 1550, poribly by DANNER a printer in MUREMBURG at that time but the associated history is some what confused.

A printing press of Dutch origin, the work of WILLEM JANSZOON. BLAEU, was available in 1620 and embochied several development although some authorities have accredited certain improvement to BLAEU which are not device for effecting the automatic return of the platen often impression. Subsequently attempts pressers wee frustrated by take of stability in the wooden france which tended to stretch under the slightest strain —– step toward was in 1790 when on American, ADAM RAMAGE brict a press which incorporated both an iron platen and bed and also included a spring device for inducing the automatic ascent of the platen offer impression.

In 1796 firming DIDOT cominoned a press with a large iron platen capable of printing a full form is stage by taking two elistinct impression. The DIDOT press was soon to be supplented by the first all iron press.

Thus, on the eve of the 19th century printed impression. The chniques of the compositor in the year 1800 had advanced very liuttle, if at all from moxons day. Printing can be traced as far back as AD 594 to the Chinese whom used block from which print were produced. However relief printing, as we know it was developed in Europe during the fifteenth century as a result of Gutenbery. Invention of movable type.

The early presses were adaptation of the winepresses in use of that time.

Few improvement or charges were made to this system. Public desire for reading which placed increasing demands of the painter technological development of the nineteenth century, the so called industrial Revolution were vast and reflected on the demand for increase for production especially of book and newspapers. Also running of the paralled with changes machine designs were the invention to the paper making and the invention of mechanical typesetting machine, faster, bigger, efficient presses were need to cope with the out put of from mechanical typesetting machines.

The most remarkable development was the introduction of iron Stan hope presses within in the period of 18 30 18 40. The rotary presses were developed for newspaper work.

Today the baie principles remained the same but the machines themselves have been developed to sophictaktion high speed electronically controlled pressed now in use.
















Printing may be simply defined as the transference of ink from an image on to STOCK.

This may be carried out in many ways but every method has each of these elements ink, image and stock.


Ink :         Enables the shape of the —— to be seen on the paper. The kind of ink depend on the process and stock, bot must be capable of:

(i)     Being deposited in a thin layer on to the image.

  • Being transferred to stock without losing the colour or strength.
  • Maintaining the shape of the image on transference.

(iv)   After being transferred, it shall adhere to the stock permanently inks are available in a wide range of colours  and  for wide range of purposes.

Image:     A prepared surface which will accept inks are for eventual transfer to the stock.

The surfaces very considerably in the form the hake depending up on the printing process being used.

The surfaces also very within any given process e.g.

Letter  press, image, type, zinc plate plastic plate, nylon plates  brass steel.

Image are produced form a variety of original copy. Sketches, artists, drawing layouts, water and oil paintings, script, photographs type images etc. type images.

Stock:      any material upon which an image can be printed. Also called substrate usually paper but may be plastic linen, tin, film.

Stock must have the following properties.

  • Dimensionally stable
  • Capable of withstanding pressure
  • Capable of withstanding normal weave and tear in use.
  • Capable of reproduce image faith fully.
  • Able of accept ink without undue absorption or rajection
  • Capable of being fed through awide range of printing pressure.




There are many printing processes that cover many requirements, only four processes colour one generally in operation in Nigeria.

They are letter press, lithography, gravune and screen printing.



Letter press principle can easily be defined as more of mechanical (physical, method of transferring ink to he stock a thin layer of ink is deposited on the relief image areas.)

This ink film is offset directly on to stock under pressure form the impression cylinder or platen.

The printing surface or image is raised in relief with the non printing areas are recessed or / on a lover plans.



The image is impresured into the paper, the indentation is sometimes visible if the back of the printed sheet is examined


  1. Allows last minutes changes and changes at run
  2. Ideal process for continuous stationery
  3. Ideal process for continuous stationery
  4. Ideal for text book printing where legibility and ease of ready are essential
  5. It process natural sparkle and clarity of detail
  6. Method for perforating and numbering can be applied during printing
  7. Large variety of job can be produced at relatively low cost.




  1. Heavy type metal and storage is rather expensive which is high lighted by problems created due to remetting and replenishing metal in terms of air pollution.
  2. Limitations of size of image areas provided for flat bed and platen work.


HAND CORRECTION:     Hand correction is usually required  to fill up required areas often casting by the mechanical comping machine as the proof reader may indicate.

Hand correction is carried on by picking types from the case. A pair of tweezers is normally used by the composition for easy access into the type form.




Composing stick is usually held in the left hand while setting a line of type from type case with the right hand. The type is assembles in the composing stick with the ink at the type is the space is placed between words as the setting proceeds. Sometimes setting rules is used to facilitate the setting when a line is set to the required measure another is started until the seetingstic  is full and litted to the qalley.









Fig shows the diagram of California job case

Show the diagram of California job case.  This is the termed a double case, it contains caps, lower case, figures spaces of different thickness and punctuation points. This case is universally used in preference to pair of case. The cantals letters are kept in separate area which is about one third of the case as shown above.


Types Alloys:  The requirements of type alloys are as  follows. Able to be case easily give a solid, sharp casting sufficiently strong to with stand distortion under reasonable pressure and long runs impervious to oxidation head Antimony and tin are good material for these requirement.

Head:       Forms the basis of printing matals, it metal

Antimony:       Is a bright crystalline and very brittle metal which tarrishes by air, it confers hardness and solidity of the types allows.

Tin:  Is a bright metal which is not tarnished by air, it possesses the property of hardening the alloys but not to the extent of antimony.



The monotype consists of two units – a keyboard and a casting machine. Each of the units makes use of 15 pound of compressed air that passes through a cooking tank per square inch.

Its fundamental principle is to cast single   type.

The monotype key board is made to produce a kind of paper ribbon / spool paper, which control is the functions of the monotype composition caster. Two key button. There are of course three special key:-

  1. The ketter space key for letter spacing of charactes.
  2. The quadder key when depressed will produce quadds on the castor.
  3. The repeater key which repeats casting of quadils character to feul a measure. Also used for centering of text matter monotype sizes are in points and sizes of set. That  e. a type may be 10pt 9 ½ set which is broad face.

Characters and letters of the type point together which the spacings required for adjustment are represented in the perforations in the tape. Normal spaces between words is put as the compositor composes and a signal is given at the completion of each line.

The compositor then records the required symbols to device the remaining space evenly. An automatic scale is used in carrying out this. The machine calculates exactly in advance how much space to put between each word.  While the tape moves through the casten, it controls plasts of compressed air that movers levers to pull a movement deposits required matrix on  to the  mouth of the mould where the hot mottern metals is —- against it to form the letter, character or space. It has a very fast casting capacity of about one hundred and fifty casts per minutes. Cast unit is pushed forwards until the whole line is completed and pushed into galley than another line starts.



There linotype land intertype machine incorporates both key board and caster. It doesn’t compose types in acceptable sence but produces lines of metal called slugs which have on their upper edges the required character. Linotype of intertype was almost conclusively used for the production of news paper and magazines bot today, the introduction of photo seterters are fastly dominating the newspaper composition.

The compositor sits before muti alphabet key board and punches the key in much the same manner as a type wrote is operated.  Brass muld called matrices are released from their position of storage in magazine. They drop through the delivery channels and one then carried to the assembly elevator, at this point space bands a re dropped between words henes of martrices and lands is  then carried to the casting mechanism where moltern metal is flushed against than coasting type slug. Immediately after casting the matrices and space bonds are revised by the first elevator to a point where they  are transferred to the distributing elevator that lift at a certain position form where they are returned to the their storage box ready for use again.



Casting of type from the monotype and linotype machines is known as hot metal,  this is because the production of much of the materials in use in this system. Type slugs, goods, roles  and leads are the products of hot metal system as they are molten metal based.


BOOK BINDING:      After the mechanization of printing there are a high demand of book and these binding operation cash making and case in remind in the hand of craptment with how out put needed mechanization too.











Letter press machines fall into three basic classes namely:-

  1. Platen
  2. Cylinder machines
  3. Rotary machines


Hand press:     The original hand printing of 1440  are still in use today. The pressure is applied by means of simple screw turning on to the flat platen. It is used in printing small job like card rebells tickers of minor quantity e.g. of such machine is Adana.


Platen Machine

There are two classes of platen machines, the high and heavy platen. The difference in these machines in not merely melter of weight and strength but the scope of job they handle. Light platen takes heles light job as circulars cards, hand bills, envelops etc. at a very slow process e.g. of right machine is clamshell (hand fed) automatic clamshell and Victoria platen heavy platens are the faster paralled approach plates machines e.g. heidlbery and thopmpsom platen they are automatic self feeding platen.


A chased forme for printing is hock up the type bed of the machine.

Diagram of machine

Impression being taken

Fig shows light or jobbing platen



Cylinder machine can be classified into three types:

  1. Stop Cylinder: It rotates slowly n ad again
  2. Two Revolution Cylinder: It revolution cylinder makes two revolution for each impression. It is very large for printing larger jobs.
  3. Single Revolution Cylinder: This machine prints in a single revolution.



Lithography is a modern method of printing that involves application of mechanical and chemical processes in printing. The printing surface and non printing surfaces are on the same plane.


Line stone which used to be a reliable lithography printing surfaces largely superseded in the modern application of lithographic printing due to the need for increased demand to compete with the contemn porory processes. Experiment were seriously made to improve the suitable surface. Highly complex matal alloye were involved and  found useful in sheet form.

Plates:     Zinc and Aluminum were found to be entirely a satisfactory lithographic printing surface. Today there are several types of matal plates in conventional use for different purposes.


They are suitable to run five thousand impression. Available in both negative or positive film will be used to transfer the image

B1 Metallic Plates: They are introduced to produce as much as one million impression without wear of being replaced.

The image is keyed to the best copier sheet while the non image back ground is of thin layer of electroplated chromium.


The Trimatalic Plates:    They has the same qualities as bi – metallic, the base consists of stainless metal covered with a layer of copper which also is coated with chromium.

Paper Plates:   They are used for line works of little quantity.

Plate Making:  The image of lithographic printing can — obtained in the following way:

  1. By Drawing on the plate with lithographic artist who draws directly on the plate with lithographic drawing ink or crayon. This system is applied for posters and other artistic commercial jobs.
  2. By transferring: To the plate, this method can be obtained by taking impression from prepared lithographic drawing a special coated paper or duplicating the existing lithographic image on to another plate which then is transferred to new plate.
  3. By Photographic Methods: The required matter to be reproduced is photographed and printed down on the plate in a way used for letter press blocks. The method is not commonly used in commercial printing


By Typing on the Plate

The required type matler required to be reproduced is typed directly on the plate using an electric type writer with a special ribbon. The purpose is to ensure evan weight of letters rules diagrams can be included by drawing on the plate with lithographic ink or crayon.








Computers have had a profound effect on every aspect of the printing industry form composition through press work and bindery. To understand about how compeers operate.

A computer is basically in adding machine which can perform the arithmetic operations of addition and subtraction much has been said about how simple computer are, but hey are, but they are actually quite complex

A computer system is made up of hardware and software. Hardware is t he physical wires monitors / motor screens keyboards, and cases from which the computer is made,  and the disks paper ribbons and other supplies used with the computer.

To do anything useful, a computer must have software.



A computer system consists of three major components

  • Memory
  • Central Processing Unit
  • Input/output devices

Each of these components is housed in some type of hardware the core of the system is (CPU) without which the computer chips that make up the central processing unit an d memory are often housed in a separate piece of hardware. Almost all computes are configured with a key board for input and a screen for data display. Together, the screen and keyboard are referred to as a terminal.

MEMORY:        Memory can be viewed as a set location, like is capable of holding a number. These numbers can represent data or they can represent instructions provided by software.

Memory does not process data, that is it does not add or subtract it. Data processing and the execution of software instruction is performed in the central processing unit.



The central processing unit can be though of as a hog switching station containing thousands of electronic switches which can be turned either on or off. Any operation performed by the typesetting computer image generation.









Ink is a delicate balance of resins, solvents, pigments and additives. There are million of ink formulations each with different characteristics.

Some of the characteristics of offset inks include. Tack viscosity, gloss, light fastness, setting and drying rates, rubresistenc etc.

TACK:      Tack or internal collusion of litho inks is one of its most important properties.



  1. Able to adhere permanently on the stock.
  2. Capable of being deposited on the image in a thin layer.




If the rate of flow and the force causing the flow are plotted as a graph as shown in fig (a) the grachient of the curve so formed is called the viscosity.

They are called paste inks. Flexo and gravure inks are vary how in viscosity.

They are liquid inks viscosity change with temperature as ink warms it becomes loss, viscous.



The method of drying is the determines the type of ink to be used in each stuff of paper. Some ink dry by one of these methods. Evaporation, Oxidation, Absorption and Radiation.

(a)    Evaporation:   The solvent portion of the ink is evaporate. This is how most web printing is dried.

(b)    Oxidation:       The ink chemically reacts with the oxygen in the air to solidity. It is how most sheet fed inks dry.

(c)    Radiation:       The radiation inks dries instantly when exposed to the proper high source.



Fountain solution is  mixture that provides perfect maintenance of the plate non image areas in clean condition while printing on lithography presses.



  • A desensitishing Agents
  • A wetting agent or other materials reducing tension
  • An acid for reinforcing the action of the desensitiser
  • A “Buffer” to inhibit corrosion or to maintain suitable ph values.

The desensiting agent can be gum or abic

The concentration which should be mixed in a correct measure of one fluid of solution to one gallon of water excess gum should be avoided in order to minimise emulsification and galaxy blanket.

Glycerine or detergent are included as wetting agents to reduce surface tension.

They must be used in small quantity because they are highly efficient. Alcohol is videly recommended instead of wetting agent.

Acids are used to improve the efficiency of the desensitising materials. The actual acid used depends purely on the type of plate. Among the acids are phosphoric acid which is not suitable for all metal surface.

Buffer is used to counteract the corrosive effect the acid used and the charge in ph which may occur from collected waist materials removed from the paper surfaces during printing.



There are considerable variety in printing papers as regards the fibre used in manufacturing. Almost all the paper are materials are rug and grass. The required properties were met by blending different fibres when preparing the furnish.


Qualities of paper

The most quality required for paper are:

  1. Good colour
  2. Smooth surface
  3. —ness of texture
  4. fairly opaqued (for easy use of the two sides of the paper).





Specialty papers



NEWSPRINT:   Made from mechanical pulp with addition of small quantity of chemical pulp to give strength. It has poor strength and turns yellow on exposure to light. Without illustrations.

MECHANICAL FINISH MF:     This has some degrees of calendering at the dry end of the paper making mocking machine which gives it low smooth, very good material for hand bills typematers without half tone.


It has special treatment by being passed through a stock of rolls known as the super calendar. Before finally heated at high speed.

CARTRIDGE:           Very closely woven twin wire paper which is very good for envelops.

OFFSET CARTRIDGE:    It has fairly white colour, very good material for muti colour jobs.

ART PAPER (COATED):  It is highly developed to meet much needed fine screen half tone blocks.

BANK AND BOND:   They are made from wide range of furnishes like rag, chemical wood and esperto, useful for heading, stationary forms, writing etc.

LEDGER PAPER:    High quality grade, used for  producing account books.

KRAFT PAPER:       Made of unbleached pure sulphate pulp.

SPECIALTY PAPER:                Specially produced for special jobs as security job, currency notes, cheques leaves.



About the year 1870 the direct lithographic flat bed machine really came to exist transfers of the kind used for metal decoration were printed on there flat bed machines.

In 1875 R. Berclay was granted for modification of the flat bed litho machine. The purpose of this medication was to enable metal to be decorated in a more direct way than the transfer method usually used.

This mechanical modification of the flat bed machine resulted in adding a second cylinder immediately above the existing one, after the fashion of the mangle the lower cylinder was covered with specially prepared card and print was  made from this the feed board was also changed or modified in the new form it consisted of a plate form at the dam person.



Towards the end of nineteenth century direct rotary lithographic machine was introduced in American, it was developed to use the metal plates. The over clumsiness (the heavy construction) and the speed limitation of the flat bed machines marked a forward step for paper printer. Again in 1903 an extra cylinder was added to the direct litho rotary design, this new achievement was put into commercial production in 1904.

Development still continues until when Rubel and the Harris brothers had inspired to establish paper rotary offset lithographic machines.

It was by then that the early  problems of the offset principles had been overcome often thirty years of practical application in Great Britain. But this does not take away  the remarkable achievement of the American engineers.

Fig shows diagram of flat but offset machine by R Barcloy in 1875. Use decorating metal sheet, by the direct method.



Fig illustrating the pimaple of offset printing as described in the text



It is cleared now that an offset print is not taken from the printing direct to paper or stock, but it firstly made on an intermediate surface (offset rubber blanket) and transferred from there to the paper. This is made possible by the method of having extra cylinder on which in stretched on offset blankets.

Today the ever increasing sophiscation of the electronic components of the new generation of these machines resulted in their high production rate and the quality of their products. Fainy washing and drying completed the process.

Tal bot method demand a good quality paper but first coated with silver Nitrate solution and the with potassium lodide, so forming light sensitive silver lodied. Increased sensitivity was abitomed by joining the paper a th— coating with gallic acid. Exposure to light follwoed after which the ladent image was developed with a gallo – mitrate of silver solution and the paper heated slightly.

Fixing washing and drying finalized the process.

The non image areas were desensitized with water is form which the greasy ink was repelled, but the image of or printing areas drown in a freasy medium attra—the ink and repelled water from where it was transfer to paper by means of pressure imported by a serap press. Senefalder patented zimk as a printing surface instead of stone in 1804 tuber hand proved the practicability of graining a metal (i.e. smoothing) of surface of a plate with abrasive, a process that provided anchorage for the image and make that retentive of moisture in order to desensitive the non image areas. The light sensetive proburities of silver bromide —-. The absence of fixer at the time was an impediment to — work.

Daguerre an d fox talbot, working independently both discovered the existence of httheatent image and demonstrated that it could be made manifest with suitable chemical treatment which they inter completed revolutionized photographic thought at that time.

The daguerrotype process necessitated the silvering of a copper plate which was subsequently made sensitivity to light by iodizing, followed by an exposure to light (sun light) followed by development of the letant image with mercury vapour.




















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Procurement systems and project organization provide the framework for implementation and development of projects. Procurement systems and project organizations are well studied and established for major developments and in developed countries in particular. When these systems are used in developing countries for major commercial, social and infrastructure developments, appropriate results are seldom achieved. This may be due to a variety of factors, which include systematic, environmental, cultural, economic, legal, political and social cultural amongst others. Not withstanding this, a major challenge in the establishment of appropriate and sustainable procurement systems and project organizational models for low-cost housing and infrastructure. The proper aims to propose a generic model of procurement system and project organization based on theory and practice as a basis for the implementation and development of low-cost housing.







1.0     INTRODUCTION                                                                   1

  • Background of the Study 1
  • Statement of the Problem 2
  • Purpose of the Study 2
  • Research Questions 3
  • Research Hypothesis 3
  • The Scope of the Study 4
  • Significance of the Study 4
  • Definition of Terms 5



2.0     LITERATURE REVIEW                                                        7

2.1     Procurement Methods                                                    7

2.2     Application of Procurement Strategies in

Nigerian Construction Industry                                     7

2.3     Statutory Duties of a Builder in any

Procurement Strategies in Nigeria                                  15

2.4     Construction Industry                                                   18



3.0     RESEARCH METHODOLOGY                                             20

  • Research Design 20
  • Population of the Study 20
  • Source of Data 22
  • Location of Data 22
  • Method of Investigation 23
  • Instrument for Data Collection                    23



  • Analysis of Data                                       24
  • Presentation of the Data                                                 24
  • Testy of Hypothesis 29
  • Discussion of Findings 32



5.0     RECOMMENDATION AND CONCLUSION                        34

  • Recommendations 34
  • Conclusion 35


References                                                                      37

Questionnaire                                                                          39










Procurement has been seen to be process of obtaining or buying supplies of something like fixed assets (land, building, etc) especially for individual and government.

Therefore, procurement strategies has become a fashionable term with our construction industry, practitioners and researchers determines the overall framework and structure of responsibilities within the process, it is also a key factor contributing to the overall client satisfaction and project success.

Procurement strategies and their application is of important in our construction industry.

However, one must not be carried by which ever method of procurement strategies proposed for a construction project, the major issue is the different types of procurement are contractual obligations, responsibilities and line of communication between the parties. One thing to remember is that which ever method that is used, the statutory duties of the professionals are always distinct and mandatory. Hence the engagement of a builder in the procuring contract is statutorily required and highly recommended whichever procurement strategy that is adopted.



The general aim of study is to ascertain by reviewing, evaluating and identifying how procurement strategies can be applied in our Nigeria construction industry. Therefore, this issue raised the researcher’s interest to know how procurement strategies can be applied in our construction industry particularly Nigerian economy.



  • To determine what are the procurement strategies;
  • To know its application in our Nigerian construction industry;
  • To know the statutory duties of a builder in construction industry;
  • To know what is construction industry.



  1. What are the procurement strategies?
  2. Where can they be applied in Nigerian construction industry?
  3. How can we know the statutory duties of a building in our construction industry?
  4. What is construction industry?



Ho:    Statutory duties of building are not necessary and mandatory in any procurement strategies use to procure a contact.

H1:     Statutory duties of a builder are necessary and mandatory in any procurement strategies use to procure a contract.

Ho:    One must not be a professional in the construction industry before contract will be awarded to him.

H1:     One must be a professional in the construction industry before contract will be awarded to him.

Ho:    One not a building before can be actually involved in the physical construction of a building.

H1:     One must be a building before he can be actually involved in the physical construction of a building.





The scope of the study is limited to only analysis of conventional procurement strategies and their application in our Nigeria construction industry.



  1. It will provide relevant information to professions on how procurement strategies can be applied in our Nigeria construction industry.
  2. It is hoped that the findings of the study will help solve the problem of what type of procurement strategies is to be use on a contract.
  3. It will assist in providing an awareness to professionals in our construction industry on application of procurement strategies.
  4. Finally, it will provide useful baseline data for future researcher’s on the similar topic.



Analysis: The details study or examination of something in order to understand more about it.

Conventional: Following the way that is generally accepted by the society.

Procurement: Process of obtaining supplies of something like fixed assets especially for individual and government.

Strategy: A plan that is intended to achieve a particular purpose.

Application: The action or an instance of putting or spreading something onto something else. It can also be seen as an instance of putting a theory, discovery, etc. to practical use.

Construction: To build something; to put or fit something together; to form something or the manner of constructing something.

Industry: This is the production of goods from raw materials, especially in factories.





There are seven methods of procurement viz:

  • Traditional or general constructing
  • Design and build
  • Two state tending
  • Public private partnership/private finance initiative
  • Management contracting
  • Construction management
  • Framework agreement.



In this method, the contract builds to a defined scope of works for a fixed price lump sum. The client retains the responsibility for the design and project team. The contractor will be appointed normally following a tender process or negotiation and will sign up to a contract for the work. There are number of standard form of building contract available for this purpose.



The client appoints a building contractor as before standard form of contract are available for this purpose to provide a completed building to an agreed cost and programme. The contractor is responsible for design and construction. The contractor can be chosen through a tender process or by; negotiation. The client can appoint a consultant to oversee the works. Maximum risk is transferred following this method of procurement although a commercial response to a design in order to address contract conditions it can result.

An alternative is to approve a contractor when designs have been developed in order to retain control of the important elements of design and specification. The design team can then transfer their contractual obligations to the contractor and complete the design on behalf of the contractor. Thus this process is called novation.


In this process, the contractor is appointed on the basis of a first stage tender which determines the level of overhead and profit for each contractor. The contractor then works with the project team during the second stage to develop the designs and establish detailed costing for separate project work elements. This process will provide for a fixed price on a detailed design basis. This provider can then enter into contract on this fixed price basis and also pursuer the opportunity to novate the design team as with the design and build procurement rouse as previously noted. This process requires a long second stage period in which to design and tender the different work element and therefore a start on site would occur later than normal.



Public private partnership (PPP) particularly private finance initiative (PFI) projects are created for the provision of services and not specifically for the exclusive provision of capital assets such as buildings. It is therefore preferable to investigate PPP’s as soon as possible after a user need has been selected as the solution. It should be noted that the tendering process in this procurement route is expensive and tending.


In comparison with other procurement of the routs, the time from commencement of the project to attaining a start on site substantially longer.




This is a fast track strategy which overlaps the design and construction stages and allows early elements of the construction process to be commenced before design has been completed.


The management contract is engaged to manage the overall contract in return for a fee. The management contractor can therefore be appointed early in the design and can advice on build-ability and programming.

In addition to the contract with the management contractor, the contracts for the individual world packages are between the management contractors. A cost plan is utilized to control the development cost although actual costs cannot be obtained until the final work package has been awarded.



This is also a fast track strategy where individual elements of the project are let before the design of later work packages or elements have been completed.


The provider will appoint a construction manager to manage the overall contract in return for a management fees as with management contracting. Also as before the project can benefit from early involvement of the contractor. In this process, the contracts for the sub-contractors are placed directly before the client will need to have a high level of involvement during the design development and the construction phases of the work as with managements contracting, the final costs will only be know once the final work element have been awarded.



Framework agreement can be establish with single suppliers to be brought together. With the relevant expertise and experience which can result in saving to both parties where a number of projects are involved.

These agreements can cover different forms of procurement including design and build, traditional, etc. The LSC are currently developing framework agreement for consultancy services across the country. These should be available for use by colleges by early 2008. Following on from this, the LSC will also be working on developing contractors’ framework.



Application can be seen as discovery, theory, etc. and putting it into practical use. Procurement strategies is of different types as early discussed. One can se that contractor can choose from the seven different methods, depending on the type of contract that is to be executed.


Firstly, in a case where the contractor is to build the design that is provided by the employer, i.e. the contractor only has responsibility for construction and not for design. Application of general contracting or traditional procurement will be suitable for such contract.


Secondly, where contractor is to take both responsibility for design and construction; that is the requirement expected from the contractor by the employer is to develop the design and construct the building. In a situation like this as the name implies, design and build procurement strategies is highly recommended where the contractor is to develop the design and construct the building.


Thirdly, in a case where early elements of the construction is allowed to be commenced before design has been completed. The contractor is engaged in this type of case to managed in overall contract and advise on buildability and programming.

The type of procurement strategies to be used in this type of contract is management contracting procurement since it is focused on the managerial type of contract.


Fourth, the type where individual elements of the project are let before the design of later work packages or elements have been completed. The contractor to handle this type of contract is advice to apply construction management.


Fifth, in a place where the contractor works with the project team to develop the design and establish detailed costing for separate project work element.

Application of two stage tender procurement will be suitable for this type of contract.


Sixth, in a case where a contractor is employ to undertake the provision of services and not specifically for the exclusion provision of capital assets such as building, public private partnership procurement will be recommended in a situation like this.


Seventh, in a case where a contractor is to supply relevant materials that will be used in the site like cement, gravels, sand etc, framework agreement procurement is to be used in order to achieve the goals required.


Finally, we can see from above how different procurement strategies can be applied to execute a contract. Also we learnt that in each procurement strategy used; the mot important thing is the responsibilities of a builder in carrying out the project.




In a building contract, a builder is to perform the following duties viz

  1. Buildability assessment
  2. Construction planning
  3. Quality management


  • Examining all production information (ie) drawing, details, specifications, schedules, bill of quantities, etc. and taking note of all buildability issues including omissions, discrepancies and interference details that adversely affect efficient and economic building productions.
  • Preparing building report including alternative and cost effectiveness solutions.
  • Presenting the buildability report.



  • Preparing online sequence of operations involving all the elements of the project;
  • Examining and reviewing the contractors method statement;
  • Examining and reviewing the following, contract’s monitoring and control document.
    • Construction method
    • Construction programme
    • Early warning system chart
    • Information requirement schedules
    • Project quality manual
    • Health and safety plan
  • Examining and reviewing the contractor’s project organization structures noting the corresponding adequacy or others;
  • Presenting construction planning report including suggestion of alternative and cost servicing method.



  • Monitoring the compliance with all relevant document/ statutory requirement in relation to developmental control, building regulations, construction regulation and statutory bodies;
  • Monitoring the implementation of the contractors and sub-contractors project quality manuals;
  • Undertaken the assessment of workmanship to project in experience and in government workmen;
  • Providing solution to technical problem on site as well as suggesting remedial action to keep project on course;
  • Monitoring the implementation and reviewing of all document monitoring control;
  • Monitoring the implementation of the health and safety plan including conciseness efforts to prevent accident, injury to persons, properties and collapse of building or port there off;
  • Attending monthly site meeting as they may become necessary to ensure smooth running project;
  • Certifying satisfactory stage completion jointly with other consultants.



Construction industry is aspect of any country’s economy, it provides facilities such as factories for manufacturing a road, airports and seaports for transportation of people and goods. Construction industry builds cities, hospital, market and homes. It also constructs a durable roads that link people of different cultures and language. Construction industry has touched people’s live by providing employment opportunities to both learned and illiterate that has lead to development of the economy. Construction industry is solving the problem of man’s shelter, infrastructure like pipe borne water, electricity, telephone for communication, etc.


Therefore, construction industry is a must in an every country’s heritage especially Nigeria that is among the developing nations.
















The descriptive is used, because it is most appropriate for survey and it provides an opportunity for collecting data from the respondents of various professionals in construction industry on procurement strategies and its application in Nigerian construction industry.


Osuala (1993) defines survey as the study of both large and small population to discover the incidence, distribution and inter-relations of sociological and psychological variables.



Ejifugha (1998) defined population in research as the entire group of people, object or institution all having at least one or two characteristics in common.


Thus the population of the study is a group that will supply information as determined by the statement of the problem.

The population of this study is basically procurement strategies and its application in Nigerian construction industry.



The research was carried out by using the two classes of data collection, viz

  1. Primary data
  2. secondary data


3.3.1 PRIMARY DATA: This was based on interviews, questionnaires and observation.

  • Interviews: Is the face to face contact to obtain a reliable and valid information required for the writing of the project;
  • Questionnaires: Is the direct asking of questions necessary that is relating to object of the study;
  • Observation: These are the interferences from both interview and questionnaires.

3.3.2 SECONDARY DATA: The secondary data was employed extensively to elucidate the researcher’s grasp of analysis of conventional procurement strategies and it’s application in Nigeria construction industry.


To achieve this review of related literature on the topic was done through text book, journals on building/magazines and internets/websites.



Data was located in various places in course of writing this project.

  1. IMT Library Campus III Enugu
  2. ESUT Library Agbani, Enugu
  3. National Library Enugu
  4. Environmental Science Library, Agbani
  5. University of Nigeria Nsukka Library (UNN) Enugu Campus.



The method of investigation was based on reviews of related literature and from people who are experts in the field of construction industry as it concerns our work.



Basically the instrument for data collection was the questionnaire the questionnaire was sub-divided into two sections, Section A aims at providing personal information about the respondents whereas Section B aims at eliciting information on different types of procurement strategies and it’s application in Nigerian construction industry.


The question was designed to related directly on the research objectives.





After experiencing an uphill task during data collection. It is now relevant to analysis and interpret the information confirmed in our questionnaires in order to test the hypothesis, present. Some factual information that will lead in achieving the objective of carrying out this work.



The data presentation and interpreted below are those gathered from the respondents regarding the basic issues raised in the research. The questionnaires were distributed as follows.

Professional builder                 –        25 (twenty five)

Site workers                            –        55 (fifty five)

Total                                        –        80 (eighty)


Remark Number of Professional Builder Number of Site Workers Total Number Returned % of Total Number
Number returned 20 40 60 70%
Number not returned 5 15 20 25%
Total shared 25 55 80 100%


From the table above, it can be observed that out of 80 questionnaires distributed, 60 questionnaires were returned and respondent too of which out of 25 given to professional builder, 20 were returned and responded while that of site workers, 40 were returned and responded to while 15 were not returned back.


Qualification No of Workers %
Standard (VI) 16 27%
WAEC 18 30%
R.S.A 6 10%
B.Sc/HND 20 33%
Total 60 100%


From the questionnaire also 20 (33%) of professional builder are holders of B.Sc/HND qualification. This is because you must have your qualification before you can be called a professional builder.



Sex No of Respondents %
Male 57 95%
Female 3 5%
Total 60 100%



The above table shows that male is more interested in working in a construction site as energy is need to carry out the work.



Statutory duties of a builder and necessary and mandatory in any procurement strategies used to procure a contract. Two elicit information that would enable us test the validity of above hypothesis, we asked both professional builder and site workers, if a statutory duties of a builder is needed in any procurement strategies used to procure a contract.



Category Remarks No of Responses %
Professional builder Yes 20 33%
Site workers No 40 67%
Total   60 100%


From the above table, it is evident that almost 20 (33%) of the professional builder prove that one must not be carried away by which ever procurement strategies used to procure a contract, that is necessary and mandatory. The statutory duties of the builder in executing the contract while 40 in workers say no because they don’t know any thing about procurement strategies only what they know is to work on the site.



You must be professional in the construction industry before contract will be awarded to you.



Responses No of Respondents %
Expert 35 58%
Quack 25 42%
Total 60 100%

So from the above table, we can be that most 35 (58%) of the respondent are professional in the construction industry. The table also shows that 25 (42%) of non-professional who can be lobbied because of their connection and richness to clear their way.



Ho:    You must not be a professional in the construction industry before contract will be awarded to you.

H1:     You must be a professional in the construction industry before contract will be awarded to you.


To test the hypothesis, the researcher made use of the expert and quack and also applied chi-square while the result will be tested at 5% level of significance is 3.84.



RESEARCH QUESTION: What are the criteria that can make someone to be awarded a contract?

Responses Professional Builder Brick Layer Total
Expert 25 10 35
Quack 12 13 25
Total 37 23 60


To ascertain the expected frequency (EF)

EF     =       RT     x        CT


From Row 1

Cell 25        =       35      x        37               =       21.6


Cell 12        =       25      x        37               =       15.4


From Row 2

Cell 10        =       35      x        23               =       13.4


Cell 13        =       25      x        23               =       9.6


Calculation of chi-square value formular

E (Fo – Fe)


Fo     =       Observed frequency or value

Fe      =       Expected value

Fo Fe Fo – Fe (Fo – Fe)2 (Fo – Fe)2


25 21.6 3.4 11.56 0.54
10 13.4 -3.4 11.56 0.86
12 15.4 -3.4 11.56 0.75
13 9.6 3.4 11.56 1.20


E       =       3.35            =       X2

X2      =       E (Fo – Fe)2                   =       3.35


Degree of freedom          =       (R – 1) (c – 1)

=       (2 – 1) (2 – 1)         =     1


Since the calculated value of X2 = 3.35 is less than the critical value of (3.84), we accept that null hypothesis (Ho) and reject the alternative hypothesis (H1)

Conclusion: You must not be a professional in the construction industry before contact will be awarded to you. Since you are not a professional builder and you awarded a contract you call up the attention of professionals to execute the contract.


The researcher set at this exercise to look onto different types of procurement strategies and its application in Nigeria construction industry. The investigation shows that some procurement methods are more important than others; respectively the major issues in the procurement strategies are the contractual obligations, responsibilities and line of communication between the parties.


Moreso, statistical analysis is performed to know the feelings of workers on the construction site and professional builder gave their support immensely, and that contributed a long way in analyzing the data.


The finding in statistical computation provides information required to make decision. These calculations may vary from single descriptive techniques to the more advanced inferential analysis. The computations are shown in sufficient detail to reveal and validate the statistical test without providing needles information or becoming overly cumbersome.


In addition, comments regarding the computation are provided to note the result and draw attention to their significance. That is the result of the computation are merely cited or quoted.














Generally, contractors should not be worried about procurement strategies to be used in an execution of contract. What should considered in any procurement method use, is the statutory duties of a professional builder handling the building contract.


The obligation of the builder in the building contract is to examine in the buildability information’s like drawing, details, specification, schedules, bill of quantities, etc. and take note of the buildability issues including omissions, discrepancies and interface details that adversely affect and economic building production.


Moreso, he prepares outline sequence of operation involving all the element of the project. Also monitoring the compliance with all relevant document/strategies requirement in relation to developmental control, building regulations, construction regulations and statutory duties.


Therefore, in procurement of any type of contract, a builder should be aware that what is expected is to apply the contractual obligation and duties in execution of the contract. The service of a builder is to manage the production process on sites construction planning and prepares construction planning procedures to ensure quality management.



The major objective of this study has been to know about procurement strategies and its application in Nigerian construction industry, in pursuant of this, the researcher has gone to different construction industry especially in Nigeria identify two procurement methods that affect a unique role of a professional builder in building production management, in pursuant of this, the researcher has gone to different construction firms especially in Nigerian that is chosen as a case study to pinpoint how procurement types can be applied in our Nigerian construction industry.


The findings of the study were quite revealing and indicated how procurement strategies can be applied in Nigerian construction industry, but most of it all is the responsibilities and contractual obligation of a builder in execution of any contract.


In the opinion of the researcher, these procurement strategies and its application in Nigerian construction industry is that in the case of application of any type of procurement depends on the type of procurement, depends in the type of contract to be executed, is the statutory duties of the builder in building project.


Finally, I hope this study will be useful to students and scholars who are interested in the analysis of conventional procurement strategies and its application in Nigerian construction industry.





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