DESIGN AND CONSTRUCTION OF AUTOMATIC GENERATOR STARTING SWITCH
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.
TABLE OF CONTENTS
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
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.
- STATEMENT OF PROBLEMS
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.
- AIM AND OBJECTIVE
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.
- SCOPE AND LIMITATION OF THE PROJECT
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.
- LITERATURE REVIEW
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.
- HISTORICAL BACK GROUND
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.
- THEORETICAL BACKGROUND
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.
- DESIGN AND CONSTRUCTION
- DESIGN METHOD
The design and construction of this automatic electronic generator starting switch was done in stages as shown in the diagram below.
3.1 THE BLOCK DIAGRAM OF AN AUTOMATIC ELECTRONIC GENERATOR STARTING SWITCH
- THE BLOCK DIAGRAM DESCRIPTION
- 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.
- 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.
- 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.
- 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.
- 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
- 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.
- 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.
- 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.
- 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.
- CONSTRUCTION METHOD
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.
BASIC PRINCIPLES OF OPERATION OF THE COMPONENTS DESCRIPTION AND USES
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.
- MODIFICATION OF RESISTOR
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
No colour 20%
- METHOD OF READING THE COLOUR CODE
From the colour table above, the value of resistor in Fig can read as:
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.
VARIABLE RESISTOR (PRESET)
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
THE LIGHT DEPENDENT RESISTOR
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.
Variable capacitors e.t.c.
It is represented symbolical in fig. 2.8 below:
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.
THE CONSTRUCTION AND OPERATION OF BJT
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.
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,
- The base – emitter junction is forward biased
- 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.
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
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.
CONSTRUCTION AND OPERATION OF A DIODE
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.
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
4.5 LIGHT EMITTING DIODE (LED)
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
4.6 MODE OF OPERATION OF THE LED
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.
TYPES OF TRANSFORMER
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.
STEP DOWN TRANSFORMER
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.
SOME USEFUL TERMS IN TRANSFORMER
(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 = 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.
- 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)
- Rechargeable battery 12V.
- LDR (light dependent resistor)
- IC UA741
- Transistor BC108