Sally Fitzgibbons Foundation

Beginning the Academic Essay

CHAPTER 1
INTRODUCTION

1.1 ABSTRACT
Industries make profit on productivity but factors such as maintenance also come into the picture as in our case it’s of power cost. As per survey they are using a power supply using transformer for step down of voltage up to 12V, but in this case the power cost is more as transformer require more power. So to reduce their power problem, we are making a SMPS. SMPS will be consuming low power and will be variable from 12V-24V. This SMPS is generally for giving and an input to the machine in the form of triggering. So to make the input as triggering we are making a triggering circuit using microcontroller. Microcontroller will sense the sensor’s located on motors and according to it the power will be given in the pulse form. The speed of motor will be too high so the sensors selected will be of high frequency. Microcontroller is selected of high speed and high frequency which can sense the sensors and give the output as pulse to the machine. Total project will be of less cost only so that it can compete with other design with better output.
This project will help to solve the problem of textile industry, specially the jacquard machine by using SMPS and triggering circuit.

1.2 INTRODUCTION
The switched mode power supply too converts the available unregulated ac or dc input voltage to a regulated dc output voltage. However in case of SMPS with input supply drawn from the ac mains, the input voltage is first rectified and filtered using a capacitor at the rectifier output. The unregulated dc voltage across the capacitor is then fed to a high frequency dc-to-dc converter. Most of the dc-to-dc converters used in SMPS circuits have an intermediate high frequency ac conversion stage to facilitate the use of a high frequency transformer for voltage scaling and isolation. In contrast, in linear power supplies with input voltage drawn from ac mains, the mains voltage is first stepped down (and isolated) to the desired magnitude using a mains frequency transformer, followed by rectification and filtering. The high frequency transformer used in a SMPS circuit is much smaller in size and weight compared to the low frequency transformer of the linear power supply circuit. The ‘Switched Mode Power Supply’ owes its name to the dc-to-dc switching converter for conversion from unregulated dc input voltage to regulated dc output voltage. The switch employed is turned ‘ON’ and ‘OFF’ (referred as switching) at a high frequency. During ‘ON’ mode the switch is in saturation mode with negligible voltage drop across the collector and emitter terminals of the switch where as in ‘OFF’ mode the switch is in cut-off mode with negligible current through the collector and emitter terminals. On the contrary the voltage regulating switch, in a linear regulator circuit, always remains in the active region. Details of some popular SMPS circuits, with provisions for incorporating high frequency transformer for voltage scaling and isolation, have been discussed in next few lessons.
As Electronic has drastically changed the world by its knowledge and by solving the problem. As the survey make in the textile industry, they required high power for maintenance of machine and they face many problem in costing of it. Textile machine contain a Jacquard machine which is used for the manufacturing of design clothes. So it has additional machinery as compare to other machine. So there are many parts which contain more power for operating.
According to the survey made in Jacquard textile industry and due to the advancement in electronic world, we have decided to solve the problem of power supply. The power supply available is costing too high which is made by other country and the machine holders cannot afford that power supply for every jacquard machine. So we have decided to make a SMPS of larger watt and also a triggering circuit using microcontroller which is combined to it.

1.3 OBJECTIVES
1. To make SMPS having fast switching and high power.
2. To design triggering circuit, to give output of SMPS in the form of pulse.
3. To solve the problem of industries regarding power system.

1.4 NEED OF PROJECT
1. SMPS is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently.
2. For provide high power supply.
This project “High power SMPS triggering circuit for textile industry” aims to resolve the above mentioned issue.

1.5 LITERATURE SURVEY
According to the survey made in Jacquard textile industry and due to the advancement in electronic world, we have decided to solve the problem of power supply. The power supply available is costing too high which is made by other country and the machine holders cannot afford that power supply for every jacquard machine. So we have decided to make a SMPS of larger watt and also a triggering circuit using microcontroller which is combined to it.
Pablo F. Miaja, Diego G. Lamar, Manuel Arias Pérez de Azpeitia, Alberto Rodríguez,
Miguel Rodríguez, and Marta M. Hernando has proved a research on – A Switching-Mode Power Supply Design Tool to Improve Learning in a Power Electronics Course
According to them a simple but accurate tool for educational purposes has been presented in this paper. This tool has been successfully used in the course “Sistemas Electrónicos de Alimentación” in the Telecommunications Engineering degree program at the University of Oviedo. It has helped students to design and build a power supply system The benefits of using this tool are reflected in the marks obtained by the students ,the efficiency in the building of the prototype, and the student spending less hours while there are more students who finish the SMPS power supply . The results of the surveys made by the university also reflect that the students valorize the subject better than the average of the subjects of the grade . Therefore, the overall quality of the student learning was improved by the use of this tool.

Knott, Arnold; Andersen, Toke Meyer; Kamby, Peter, Pedersen, Jeppe Arnsdorf, Madsen, Mickey Pierre, Kovacevic, Milovan, Andersen and Michael A. E has proved a research on – Evolution of Very High Frequency Power Supplies
The merge of techniques used in radio communication electronics and power electronics was pointed out. The development through the previous decades has been revisited and recent developments were summarized. Remaining challenges and the latest advances were described. The implementations of numerous VHF converters were presented. Among them are low-power, high-step-down converters with a switching frequency of 70 MHz and an efficiency beyond 70 % as well as a 120 MHz, 9 W LED driver with an efficiency up to 89 %. Both converters maintain high efficiencies over a wide load range.

Zameer Ahmad and S.N. Singh has proved a research on – Microcontroller Based Advanced Triggering Circuit for Converters/Inverters
The use of Microcontroller (8051) based triggering circuit provides us a large number of advantages. The efficient control of delay angle and incorporation of feedback signal from ADC is main advantage. There is a greater scope for further improvement just by changing the program but not hardware configuration. Its long life and no fatigue are the most appreciated characteristics. The generated triggering pulse is synchronised with supply frequency and recorded for various delay angle. Zero Crossing detector (ZCD) is used to detect the zero crossing of the supply. The performance of controller is found satisfactory. In general switching control mode as well as specific application. The wave form records shows accuracy of delay of control pulse and also show the satisfactory performance of whole setup.

CHAPTER 2
HARDWARE DESIGN

2.1 BLOCK DIAGRAM

Figure 2.1: Block Diagram Of Project

2.1.1 Block diagram description

The system consist of SMPS (Switch Mode Power Supply) and triggering circuit which will sense the IR sensors and will give information to the microcontroller used and according to it the power will be supplied by SMPS. The input of 230 volts and output of SMPS is 12 voltage and 15 Ampere. IR sensors are used so that the time span of providing power is known to the system. SMPS design varies with the change in output. This system will solve the problem of power supply. This SMPS is generally for giving and an input to the machine in the form of triggering. So to make the input as triggering we are making a triggering circuit using microcontroller. So we have decided to make a SMPS of larger watt and also a triggering circuit using microcontroller which is combined to it.
We have also used GPS and GSM module to detect the GPS co-ordinates and send them to the registered mobile number. This makes the system more reliable as compared to all the previous made systems

2.2 CIRCUIT DIAGRAM

Figure 2.2.a: Circuit Diagram Of SMPS

Figure 2.2.b: Circuit Diagram Of Triggering Circuit.

Figure 2.3.c: Complete Project.

2.2.1 Description of Circuit Diagram
It’s a pretty standard sort of supply – half-bridge topology, with a single KA7500B PWM controller chip running everything. Isolation is provided by the base drive transformer, so there’s no need for op to coupler feedback.

Input filter and HV supply
1. This is a pretty bog-standard circuit.
2. Fuse, common-mode choke, filter capacitors to block/absorb any HF interference, the a full-wave bridge rectifier and two smoothing caps.
3. Note that C2 and C3 are in series – this is so the midpoint can be used as a voltage at half the full supply voltage.
4. One end of the transformer’s primary goes to here, the other end gets switched between 0V and the full supply voltage, so the primary sees ± half the full supply voltage.
5. SW1 is the switch to select between 110V/230V operation.
6. For 230V operation, the switch is open, and the voltage across C2+C3 is the peak AC input voltage.
7. For 110V operation, the switch is closed, and the bridge + the two capacitors act as a voltage doubler so the total voltage across C2+C3 is now twice the peak AC input voltage.

Bridge Transistors, Base Drive and Main Transformer
1. TR1 is the base drive transformer, it can also be called as “gate” transformer sometimes. TR2 is the main transformer.
2. The two bridge transistors (Q4 ; Q1) switch one end of the transformer’s primary between 0V and the full DC supply voltage.
3. First, the extra resistors such as R14, R13, R8, R4 bias the main transistors on slightly during startup.
4. One transistor will turn on slightly quicker than the other. If you look closely, note that the bottom end of the main transformer’s primary isn’t connected directly to the midpoint of the two transistors – rather, it goes through a winding on the base drive transformer.
5. As current starts flowing in the main transformer primary, it induces a current in the base transformer windings, one of which will assist the already-on transistor, switching it fully on.
6. This will provide enough power to get the auxiliary supply up (it reaches about 10V, but that can vary), and start the KA7500B running, at which point it takes over and controls the switching of the bridge transistors.
7. Another extremely neat feature of this configuration, in addition to the self-starting capability, is that the KA7500B doesn’t have to provide the full base drive current to the bridge transistors – the base drive current actually comes from the primary current, coupled through the base drive transformer.
8. The drive transistors on the primary of the base transformer simply manage to control which of the main transistors is held on by the primary current.

Output Rectification ; Smoothing
1. For the main DC output, there’s a center-tapped secondary with a couple of power Schottky diodes doing the rectification. Some smoothing caps, indicator LED, and a big filter inductor (L1).
2. J1,J4,J7 are low-resistance wire jumpers which are used as a current sensing resistor. Since the PCB is designed with different configurations of power supply in mind (voltages and output currents), there are positions for six jumpers – by changing the number of jumpers, the current limit level can be changed to suit different supplies.

Feedback/Regulation/Current Limiting
1. The voltage sense divider (dotted box on far left of schematic) results in an adjustment range of about 10-15V with the default component values.
2. The inverting input (pin 2) goes to a fixed 2.5V reference (half of Vref).
3. The TL494 adjusts its output duty cycle to make the output from the divider equal to 2.5V.
4. The components marked “voltage loop compensation” are voodoo and have the effect of reducing feedback gain at higher frequencies.
5. Capacitors C31 and C28 in the voltage divider also perform loop compensation.
6. Op-amp #2 of the TL494 is used for current limiting. The noninverting input (pin 16) is grounded via R24. The inverting input (pin 15) is tied to Vref (5V) by R21, and to the current sense shunt (parallel combination of J1, J4, J7) by R35.
7. The way this works – if no current is flowing in the output, the current sense shunt has no voltage across it, so the voltage appearing at pin 15 of the TL494 will be (750/(750+68k))*5 = 55mV. As current flow increases, the current sense shunt will pull the end of R35 more and more negative until, when the voltage from the shunt reaches -55mV, pin 15 reaches 0V and the #2 op-amp output will trip, reducing the PWM duty at the output.
8. This happens with an output current of 55mV/(3.9mR/3) = 42A – a little bit higher than the advertised limit of 33A, but I am probably off in my measurement of the current shunt resistances. Several components (C29 + R36) are also used to compensate the current limit loop.

Soft Start
1. Pin 4 of the KA7500B is called the dead-time control input and can be used to implement a soft-start feature.
2. C24 is initially discharged, so when power is applied, the DTC pin is held high. This inhibits the output. As C24 gradually charges up (via R19), pin 4 drops in voltage, which slowly decreases the dead time, bringing the output up to its operating level. Pin 4 settles at about 0.4V.
3. Pin 4 of the TL494 is called the dead-time control input and can be used to implement a soft-start feature. C24 is initially discharged, so when power is applied, the DTC pin is held high. This inhibits the output. As C24 gradually charges up (via R19), pin 4 drops in voltage, which slowly decreases the dead time, bringing the output up to its operating level. Pin 4 settles at about 0.4V.

2.2.2 Calculation for Circuit

Step 1: Setting the Output Voltage

The KA7500Bs output voltage can be adjusted between 0.9V and 0.9 x VIN. The output using the resis¬tors connected to the FB pin is calculated as follows:

Step 2: Setting the Switching Frequency

The KA7500B can operate between 1kHz and 300kHz. The RT pin is used to set the regulator’s switching fre¬quency (fSW). RT is connected to 22k?, which gives 100kHz. This is calculated using the following equation:

where RRT is in k? and fSW is in kHz.
The switching frequency fSW = 100kHz and RRT = 22k?, 22k? is chosen here.

Step 3: Selecting the Output Inductor

The LX pin is connected to the switching node of the inductor. The value of the inductor is calculated as follows:

where VOUT = 4V, fSW = 100kHz, and L = 18.1?H. A 15.6?H value is chosen for this design.

Step 4: Selecting the Output and Soft-Start Capacitor

The soft-start feature ramps up the output voltage slowly, reducing input inrush current during startup. A capacitor connected from SS to SGND determines the soft-start. This soft capacitor depends upon the output capacitor. The output capacitance can be calculated as follows:
where ISTEP is the load current step, tRESPONSE is the response time of the controller, ?VOUT is the allowable output voltage deviation, fC is the target closed-loop crossover frequency, and fSW is the switching frequency. Choose fC to be 1/9th of fSW because in this design the switching frequency is less than 450kHz.

Substitute the following values in the above equations:
ISTEP = 2.5A
?VOUT = 0.12V
fc = (100k/9)
fSW = 100kHz
tRESPONSE = 39.7?s
Hence, the 1nF capacitors are selected in parallel for the nominal value.
The soft-start capacitance (CSS) is calculated as follows:

CSS ? 28 x 10-6 x COUT x VOUT
COUT is the selected output capacitance:
CSS ? 28 x 10-6 x 19 x 10-6 x 4
where CSS ? 1.12nF. CSS = 1nF is considered the nom¬inal value.

Step 5 Input Capacitor Selector

The input filter capacitor reduces peak currents drawn from the power source and reduces noise and voltage ripple on the input caused by the circuit’s switching. The input capacitor RMS current requirement (IRMS) is defined by the following equation:

Substituting the values:
IOUT(MAX) = 15A
VIN = 24V
VOUT = 12V
IRMS = 15.62A

where IOUT(MAX) is the maximum load current.
IRMS has a maximum value when the input voltage equals twice the output voltage (VIN = 2 x VOUT),
so IRMS(MAX) = IOUT(MAX)/2A.
Calculate the input capacitance using the following equation:

Substituting the values:
I(out)= 24A
D=V(out)/V(in)=2
n=98%
Fsw=100kHz
V(in)=0.5

where the input capacitor =4.7 uF

CHAPTER 3
COMPONENTS REQUIRED

3.1 PIC MICROCONTROLLER (PIC 16F877A):

Figure 3.1.a: Circuit Diagram Of Controller

A microcontroller is a compact integrated circuit designed to govern a specific operation in an embedded system. A typical microcontroller includes a processor, memory and input/output (I/O) peripherals on a single chip. PIC microcontrollers are very popular and industrialists; this is only cause of wide availability, low cost, large user base & serial programming capability. In our project we are choosing a PIC18F4520 microcontroller because of its maximum speed, amount of RAM and sufficient number of I/O pins.

Figure 3.1.b: PIC Microcontroller

3.1.1 Features

• 10 bit inbuilt ADC 8 channels (an0 – an7)
• 40 pin i/o (a0-a5,b0-b7,d0-d7,c0-c7, e0-e2)
• Reset pin no. 1 (active low)
• Crystal pins at 13 -14 pin
• 1 serial half duplex port (rc7 (RX.) –rc6 (TX.))
• Interrupts (rb0 (int0)- rb1 (int1))
• Inbuilt i2c bus (rc3 (SCL) – rc4(SDA))
• Inbuilt SPI bus (SS,SDI,SCK,CS)

3.1.2 Pin diagram

Figure 3.1.2: Pin Configuration Of PIC16F877A

3.1.3 Reset Circuit
Reset is used for putting the microcontroller into a ‘known’ condition. That practically means that microcontroller can behave rather inaccurately under certain undesirable conditions. In order to continue its proper functioning it has to be reset, meaning all registers would be placed in a starting position. Reset is not only used when microcontroller doesn’t behave the way we want it to, but can also be used when trying out a device as an interrupt in program execution, or to get a microcontroller ready when loading a program.
In order to prevent from bringing a logical zero to MCLR pin accidentally, MCLR has to be connected via resistor to the positive supply pole ANDa capacitor from MCLR to the ground. Resistor should be between 5 and 10K and the capacitor can be in between 1µf tp 10 µf. This kind of resistor capacitor combination ,gives the rc time delay for the µc to reset properly

Figure 3.1.3: Reset Circuit
As shown in the above circuit we are connecting an RC circuit to the MCLR (pin1) of µC. The PIC µC has an active low reset, therefore we connect an RC circuit. As shown the capacitor is initially at 0v. It charges via the supply through a 10 kohm resistance in series, therefore the reset time of our circuit is:
R*C = 10kohm * 10 µf = 100 msec
Recommended time of reset = 1 msec
Here the RC time can vary from 10 m sec to 100 msec.

3.1.4 Crystal Circuit
Pins OSC1 ; OSC2 are provided for connecting a resonant network to form oscillator. Typically a quartz crystal and capacitors are employed. The crystal frequency is the basic internal clock frequency of the microcontroller. The manufacturers make available PIC designs that can run at specified maximum ; minimum frequencies, typically 1 MHz to 16 MHz.

P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1

State 1 State 2 State 3 State 4 State 5 State 6
One Machine Cycle
Figure 3.1.4.a: Crystal Pulse.

Figure 3.1.4.b: Crystal Circuit.
Here we are connecting twp ceramic capacitors which are basically used for filtering. In other words to give a pure square wave to the µC we are connecting the two capacitors.
The basic rule for placing the crystal on the board is that it should be as close to the µC as possible to avoid any interference in the clock.
Reason for 11.0592 MHz
Serial data communication needs often dictate the frequency of the oscillator because of the requirement that internal counters must divide the basic clock rate to yield standard communication baud rates. If the basic clock frequency is not divisible without a reminder, then the resulting communication is not standard.

Table 3.1.4: Buad Rate Formule.
Here we keep
SPBRG = 143; for 4800 baud rate and 71 for 9600 baud rate
BRGH = 1; high speed
Therefore 11.0592Mhz / 16 (143 +1);
11.0592Mhz / 16(144);
11.0592Mhz / 2304;
4800 bits/sec (a standard communication baud rate)

3.2 16X2 LCD
LCD (Liquid Crystal Display) screen is an electronic display module and find a wide range of applications. A 16×2 LCD display is very basic module and is very commonly used in various devices and circuits. These modules are preferred over seven segments and other multi segment LEDs. The reasons being: LCDs are economical; easily programmable; have no limitation of displaying special ; even custom characters (unlike in seven segments), animations and so on.
A 16×2 LCD means it can display 16 characters per line and there are 2 such lines. In this LCD each character is displayed in 5×7 pixel matrix. This LCD has two registers, namely, Command and Data. The command register stores the command instructions given to the LCD. A command is an instruction given to LCD to do a predefined task like initializing it, clearing its screen, setting the cursor position, controlling display etc. The data register stores the data to be displayed on the LCD. The data is the ASCII value of the character to be displayed on the LCD. Click to learn more about internal structure of a LCD.
The purpose of using 16×2 LCD in our project is to display all the parameters of solar panel and is connected to pin no 37 and 38 of microcontroller.

Figure 3.2: 16×2 LCD

3.2.1 Interface pin description

Figure 3.2.1: Pin Description Of 16×2 LCD

3.2.2 Pin Details

Table 3.2.2: Pin Description Of 16×2 LCD

3.2.3 Features
• 16×2 matrix
• Low power operation support: 2.7 to 5.5V.
• Duty cycle: 1/16.
• Connector for standard 0.1-pitch pin headers.

3.3 IR SENSORS

Figure 3.3.a: Circuit Diagram Of IR Transmitter
Figure 3.3.b: Circuit Diagram Of IR Receiver

An infrared sensor is an electronic device, that emits in order to sense some aspects of the surroundings. An IR sensor can measure the heat of an object as well as detects the motion. These types of sensors measures only infrared radiation, rather than emitting it that is called as a passive IR sensor. Usually in the infrared spectrum, all the objects radiate some form of thermal radiations. These types of radiations are invisible to our eyes, that can be detected by an infrared sensor. The emitter is simply an IR LED (Light Emitting Diode) and the detector is simply an IR photodiode which is sensitive to IR light of the same wavelength as that emitted by the IR LED. When IR light falls on the photodiode, the resistances and these output voltages, change in proportion to the magnitude of the IR light received.

Figure 3.3.c: IR Sensor
An infrared sensor circuit is one of the basic and popular sensor modules in an electronic device. This sensor is analogous to human’s visionary senses, which can be used to detect obstacles and it is one of the common applications in real time.
This circuit comprises of the following components:
• LM358 IC 2 IR transmitter and receiver pair
• Resistors of the range of kilo ohms.
• Variable resistors.
• LED (Light Emitting Diode).

3.4 POWER SUPPLY

Figure 3.4: Circuit Diagram of Power Supply
The basic step in the designing of any system is to design the power supply required for
that system. The steps involved in the designing of the power supply are as follows,

1) Determine the total current that the system sinks from the supply.
2) Determine the voltage rating required for the different components.

The bridge rectifier and capacitor i/p filter produce an unregulated DC voltage which is applied at the I/P of 7805.As the minimum dropout voltage is 2v for IC 7805, the voltage applied at the input terminal should be at least 7 Volts.
C1 (1000 µf / 65v) is the filter capacitor and C2 and C3 (0.1 pf) is to be connected across the regulator to improve the transient response of the regulator.
Assuming the drop out voltage to be 2 volts, the minimum DV voltage across the capacitor C1 should be equal to 7volts (at least).

Power supply design of the Project:

The average voltage at the output of a bridge rectifier capacitor filter combination is given by

Vin(DC) = Vm – Idc / 4 f C1

Where, Vm=?2 Vs and Vs = rms secondary voltage

Assuming Idc to be equal to max. load current, say 100mA

C = 1000 Gf / 65v, f=50hHz

19 = Vm – 0.1 / 4*50*1000*10¯6

19= Vm – 0.1 / 0.2

Vm=19.5 volts

Hence the RMS secondary Voltage

Vrms = Vm / ?2

= 19.5 /?2

=19,5 / 1.4421

=13.5 volts

So we can select a 15v secondary Voltage

In our system most of the components used require 5 V as operating voltage such
as micro controller, MAX 232, MCT2E etc. The total current, which our circuit
sinks from the power supply, is not more than 100 mA. We have used Regulator
IC 7805 that gives output voltage of 5V. The minimum input voltage required
for the 7805 is near about 7 v. Therefore we have used the transformer with the voltage rating 230v-10v and current rating 500 mA. The output of the transformer is 12 V AC. This Ac voltage is converted into 12 V DC by Bridge rectifier circuit.

The reasons for choosing the bridge rectifier are
a) The TUF is increased to 0.812 as compared the full wave rectifier.
b) The PIV across each diode is the peak voltage across the load = Vm, not 2Vm as in the two diode rectifier
Output of the bridge rectifier is not pure DC and contains some AC some AC ripples in it. To remove these ripples we have used capacitive filter, which smoothens the rippled out put that we apply to 7805 regulators IC that gives 5V DC. We preferred to choose capacitor filters since it is cost effective, readily available and not too bulky.

3.4.1 Transformer

Step down transformer: is one whose secondary voltage is less than its primary voltage. It is designed to reduce the voltage from the primary winding to the secondary winding. This kind of transformer “steps down” the voltage applied to it.
As a step-down1 unit, the transformer converts high-voltage, low-current power into low-voltage, high-current power. The larger-gauge wire used in the secondary winding is necessary due to the increase in current. The primary winding, which doesn’t have to conduct as much current, may be made of smaller-gauge wire.

Figure 3.4.1: Transformer

3.4.2 Bridge Rectifier

The bridge rectifier provides full wave rectification from a two wire AC input. It is formed of powerdiode BY127. The ac input voltage is applied to the diagonally opposite ends of the bridge.The loadresistance is connected between the other two ends of the bridge. For the positive half cycle of the inputac voltage, diodes D1 and D3 conduct, whereas diodes D2 and D4 remain in the OFF state. The conductingdiodes will be in series with the load resistance RL and hence the load current flows through RL 04.
For thenegative half cycle of the input ac voltage, diodes D2 and D4 conduct whereas, D1 and D3 remain OFF. Theconducting diodes D2 and D4 will be in series with the load resistance RL and hence the current flowsthrough RL in the same direction as in the previous half cycle. Thus a bi-directional wave is converted into aunidirectional wave.

Figure 3.4.2: Bridge Rectifier

3.4.3 Diode

A diode is a two terminal electronic component that conducts primarily in one direction. It has low resistance to the current in one direction and high resistance in other. The most common function of a diode is to allow an electric current to pass in one direction while blocking current in the opposite direction. This unidirectional behaviour is called rectification and it is used to convert ac to dc. Here we use 1N4007 diodes.

Figure 3.4.3: 1N4007 Diode

3.4.4 Regulator IC-7805

The +5 volt power supply is based on the commercial 7805 voltage regulator IC. This IC contains all thecircuitry needed to accept any input voltage from 8 to 18 volts and produce a steady +5 volt output,accurate to within 5% (0.25 volt). It also contains current-limiting circuitry and thermal overloadprotection, so that the IC won’t be damaged in case of excessive load current; it will reduce its outputvoltage instead 04.

Figure 3.4.4: Regulator IC-7805

Specifications
• Output Voltage 5V.
• Ripple rejection.
• Ratio78dB.
• Multicolor Display Board24.

Table 3.4.4: Pin description of IC LM 7805
Pin No. Description Name
1 Input voltage (5V-18V) Input
2 Ground (0V) Ground
3 Regulated output; 5V (4.8V-5.2V) Output

3.4.5. Capacitor

Capacitor is a passive 2 terminal electrical component that stores electrical energy when they are connected to battery or some other charging circuit. The effect of capacitor is known as capacitance. The capacitor contains 2 metallic plates that are separated by some form of insulation. Capacitance is usually measured in the farad unit. They are commonly placed in electronic components and are used to maintain a power supply while the device is unplugged and without a battery for a short time.
Here, in our project we are using 0.1uf, 100uf, 450uf, 470uf.

Figure 3.4.5: Capacitors

3.4.6 Resistors

A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. Resistors act to reduce current flow, and, at the same time, act to lower voltage levels within circuits. Here, in our project we are using 10?, 1k?, 2.2K? and 10K?.

Figure 3.4.6: (a) Resistor (b) Rheostat (variable resistor) And (c) Potentiometer

3.4.7 KA7500B SMPS Controller

The KA7500B is used for the control circuit of the PWM switching regulator. The KA7500B consists of 5V reference voltage circuit, two error amplifiers, a flip flop, an output control circuit, a PWM comparator, a dead time comparator and an oscillator. This device can be operated in the switching frequency of 1kHz to 300kHz.

Figure 3.4.7.a: KA7500B

Features
1. Internal Regulator Provides a Stable 5V Reference Supply Trimmed to 5%
2. Uncommitted Output TR for 200mA Sink or Source Current
3. Output Control for Push-Pull or Single Ended Operation
4. Variable Duty Cycle by Dead Time Control (Pin 4) Complete PWM Control Circuit
5. On-Chip Oscillator with Master or Slave Operation
6. Internal Circuit Prohibits Double Pulse at Either Output

Figure 3.4.7.b: Block diagram of KA7500B

Table 3.4.7: Absolute Maximum Ratings

3.4.8 HSC1815

Description

1. NPN epitaxial planar transistor

2. The HSC1815 is designed for use in driver stage of AF amplifier general purpose amplification.

Figure 3.4.8: Description of HSC1815

CHAPTER 4
PCB DESIGNING
4.1 PCB Layout and Artwork

Figure 4.1.a: SMPS Circuit Track Layout.

Figure 4.1.b: Triggering Circuit Layout.

Layout basically means placing or arranging things in a specific order on the PCB. Layout means placing of components in an order. This placement is made such that the interconnection lengths are optimal. At the same time, it also aims at providing accessibility to the components for insertion testing and repair.
The PCB layout is the starting point for the final artwork preparation layout design should reflect the concept of final equipment.
There are several factors, which we must keep in mind for placing the layout.
4.1.1 Schematic Diagram
The schematic diagram forms main input document for preparation of the layout for this purpose the software for PCB design, PROTEUS was used.
4.1.2 Electrical and thermal requirement
The PCB designer must be aware of the circuit performance in critical aspects of the same concerning electrical conditions and the environment to be used in.
4.1.3 Mechanical requirement
The designer should have the information about physical size of the board, type of installation of board (vertical/horizontal). The method of cooling adopted, front panel operated components etc.
4.1.4 Component placing requirement
All components are too placed first in a configuration that demands only the minimum length for critical conductors. These key components are placed first and the others are grouped around like satellites.
4.1.5 Components mounting requirements
All components must be placed parallel to one another as far as possible i.e. in the same direction and orientation mechanical over stressing of solder should be avoided.
4.1.6 Layout Methodology
For proper layout design minimal steps to be followed are:

• Get the final circuit diagram and component list.
• Choose the board types, single sided / double sided / multilayer
• Identify the appropriate scale for layout.
• Select suitable grid pattern.
• Choose the correct board size keeping in view the constraints.
• Select appropriate layout technique, manual / automated.
• Document in the form of the layout scale.

4.2ART Work
Art work is accurately scaled configuration of the printed circuit from which the master pattern is made photographically.
4.2.2 Art Work Rule
Rules followed while selecting artwork symbol takes:
• Minimum spacing between conductor and pad should be 0 / 35 mm in 1:1 scale.
• Minimum spacing between parallel conductors should be 0.4 mm in 1:1 scale.
• The area of non-PTH solder pad should not be less than 5 sq.mm.
• The width of current carrying conductors should be determined for max. temp. rise of 20 ?C.

4.2.3 General Art Work Rules
When there is higher conductor density assumes the conductors parallel to any one of the edge of the board.
When conductors have to be placed in other direction preference should be given to the 45? direction or to the 30? / 60? direction.
Whenever there is sufficient space available the conductors can be run in any direction so as to achieve sorted possible interconnection.
As far as possible, design and the conductor on the solder pad.
Conductor forming sharp internal angles must be avoided.
When a member of conductor has to run between two pads the conductor lines are run perpendicular w.r.t. the center-to-center line of pair of pads.
Equally distributed spacing is to be provided when three or more conductors run along a direction and / or between two pads.
Minimum spacing is provided when three or more lines run along a direction and / or between two pads.
The diameter of solder pad should be approximately 8 times the drilled whole diameter

CHAPTER 5
SOFTWARE PART
5.1 MPLAB

The MPLAB IDE has both plug-in modules and built-in components to configure the
system for a variety of software and hardware tools.

5.1.1 MPLAB IDE Built-In Components

The built-in components consist of:
• Project Manager
• Editor
• Assembler/Linker and Language tool
• Debugger
• Executions engine
• Project Manager:
• The project manager provides integration and communication between the Integrated
• Development Editor and the language tools.

Figure 5.1.1: MPLAB IDE Project Manager.

5.1.2 Editor

The editor is a full-featured programmer’s text editor that also treats as a window into the debugger.

5.1.3 Assembler/Linker and Language Tools

The assembler can be used to assemble a single file, and/or can be used with a linker to build a project from separate source files, libraries and recompiled objects. The linker is liable for positioning the compiled code into memory areas of the mark microcontroller.

5.1.4 Debugger

The Microchip debugger allows single stepping, breakpoints, watch windows and all the features of a modern debugger for the MPLAB IDE. It works in coincidence with the editor to reference information from the target being debugged back to the source code

5.1.5 Execution Engines

There are software simulators in MPLAB IDE for all PIC MCU and ds PIC DSC devices. These simulators use the PC to simulate the instructions and some peripheral functions of the PIC MCU and ds PIC DSC devices. Optional in-circuit emulators and
in-circuit debuggers are also available to test code as it runs in the applications
hardware
.

5.2 ALGORITHM

1. Start
2. Read first IR sensor
3. Read until the second IR sensor come and note the time
If both the sensors are sensed then
Give output of SMPS
Output will be for the time taken to sense the IR sensor’s
Stop the output as the time is over
Else give output and wait
4. Wait for some time
5. Again repeat the same process
6. Check whether the output is proper
7. Run the process until the system is on
8. Stop

?
5.3 FLOWCHART

5.4 CODE

#include
#include “tempdef.c”
bit timLB2,timLB1;
int timLED2,timLED1;
void interrupt isr(void)
{
if(TMR1IF)
{
TMR1IF = 0 ;
TMR1H = TIMER1_RELOADH ;
TMR1L = TIMER1_RELOADL ;
delaycnt++ ;
if(RxFlag && Rxcnt) Rxcnt– ;
milisec++ ;
if(timLB1 && timLED1)timLED1–;
if(timLB1 && !timLED1)LED1=1;
if(timLB2 && timLED2)timLED2–;
if(timLB2 && !timLED2)LED2=1;
if(milisec >= 1000)
{
milisec = 0 ;
Second++;
}
}
if(ADIF)
{
ADIF = 0 ;
adcflag = 1 ;
adcval = (((UINT)ADRESH)

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