The Buggy Project

BATTERY

The battery used is an eight cell battery from an old laptop 9,6V NiMH.
I removed the battery and I noticed that two of the cells were broken (I think this is why they couldn't fully charge) so I used the good condition ones. They give enough power to drive two DC motors. Voltage from battery goes through a 5V voltage regulator (LM7805) to supply the microcontroller.

DC MOTORS

Geared motors are wired to a L293D motor driver.
The driver has two supply voltages VCC1 and VCC2. Where VCC1 on 16th pin is the logic 5V supply and VCC2 on 8th leg is to supply the motors. 
I connected the 8th leg straight to battery.
Output power for both motors is controlled by PWM from PIC microcontroller (both EN pins from driver go to two independent PWM outputs of PIC).

I had to put some grease into the gearboxes, bacause the motors were a bitnoisy.
(In my Videos you can find the video which shows the noise differene)

Main Board

This was a real challenge because I have never done a double layer PCB before.
First thing I did a quick plan on paper of what I want to achieve, numbers of Digital pins used, analog, etc. Then I created a schematic in Proteus, after this I moved to the PCB design using Proteus.

Last step was to print top and bottom layer on a photo paper using laser printer and the PCB was ready for etching. 

It took 4 days to finish the main PCB with planning, etching, drilling and soldering.
The most boring process was to make vias to join top and bottom traces together. I have used a piece of wire going through the hole then it was soldered from both sides.

NOTE: Make sure the schematic is correct before you start etching your PCB, to avoid cutting tracks.

The PCB is painted with red glass paint, to protect the copper from oxidation and looks a bit better.

You can find a lot of tutorials on internet of how to etch the PCB, how to prepare the copper etc...

Click on link button.