This is a basic design for a 3-channel PWM controller, like you might use to control a string of 12v RGB LEDs, like these, maybe:
dealextreme.com/p/rgb-multicolored-1-meter-30-led-6w-light-strip-dc-12v-14965 (fun, because you can just cut it to the length you want, in minimum units of ~3 inches)
I've got a few different things I want to do with this, but it was mainly a way for me to try designing and etching my first PCB.
* Custom Arudino bootloader (kinda)
* Three 200ma(ea) 12v PWM channels
* Three analog input pins
* Runs on 12v (good for use in a car!)
* Minimal part count
* All the photos are of the first design, which as you can see, had a lot of mistakes requiring jumpering and trace-cutting. I think they have all been solved in the uploaded schematic, but I haven't had an opportunity to print a new one to test.
* The first design schematics are lost, sorry. :(
* I'm using a custom arduino bootloader (will be provided below) and included an arduino pinout but I cannot get the arduino programmer to communicate with my Atmega8. It does serial comms over those lines fine, otherwise. Help appreciated.
* I've /just/ used this in my first design (to be published shortly) so I'm still testing it. Seems to work well these last few hours at least!
* The transistor breakout board (the tc* files) I had to build on a protoboard as we've got a cold snap and I'm a wimp who will not go outside to etch if the weather is less than perfect. As soon as it warms up a bit I'll be printing that and the new mainboard. I might combine them.