Chapter 4: PCB Design Process

Chapter 4
PCB DESIGN

4.1 PCB DESIGNING STEPS

The most important requirement of this project was to build a PCB with minimum weight and size. A Zero PCB is a drilled board. Drilling process removes a lot of material from board, and the weight is reduced. Designing method is as follows.

1. Decide proper places for components

2. Actual Placement of components on Zero PCB

3. Connecting Tracks with solid wires

4. Testing for continuity and Debugging

Four PCBs are designed in this project. The main PCB, the LED module, and power supply PCB. All PCBs are constructed on simple zero PCB, and interconnection of components was done by single stranded wires.

Chapter 5
Results and Conclusions

5.1 Interrupt module testing results
5.2

Supply voltage given to Pin. No. 1(Collector) and Pin.No.3(Anode) of MOC7811=5.5V
Output voltage obtained at Pin.No.1 of MOC 7811 without interrupt=5.21v
Output voltage obtained at Pin.No.1 of MOC7811 with interrupt=0.08V

5.2 DC MOTOR RPM TESTING

DC Motor used in this project is 12 V dc motor which is tested by using digital contact-less tachometer. Arrangement was made so that the sensing circuit gives high to low pulse for each completion of revolution. By measuring the time difference between two successive pulses RPS can be calculated which further provide RPM value, as shown below:
Power supply given to DC Motor = 9V
Time interval between two successive pulses as seen on CRO = 30.4ms
RPS = 1 / (30.4ms) =32.89
RPS = 33
RPM= 33x60

5.3 POWER SUPPLY MODULE TESTING Power supply module was designed to provide 5V DC power supply necessary to drive both motor and circuit. AC input is given from 9V 750mA transformer. Results are as follows.

Input voltage, Vs=9V AC

Output voltage observed , Vo = 4.92V

Connect the power cord to the AC mains power supply of 230V.
2. Check whether the output of IC LM7805 is 5V or not. The power supply is ok if the output is 5V.
3. Now, connect the voltmeter’s probes to the motor’s terminals. 5V is the desired voltage there.
4. See if the YELLOW LED on the main PCB is glowing or not. Glowing LED indicates that it is receiving proper input voltage and so, on the Vcc of the microcontroller.
5. Adjust the interrupt ( Red strip) so that it easily passes through the sensor.
6. Check if the Pin 6 of the microcontroller receives LOW voltage when interrupt occurs, and HIGH voltage, otherwise.
7. Finally, ensure that the standing assembly does not have any discrepancies.

6.2 TROUBLESHOOTING MANUAL

1. Output voltage of LM7805 is not