I have good news today! I got my R9 prototype boards the other day, and today successfully assembled and tested it today. I used whatever random parts io could find, and it still works!! I had to test with external arduino. 3. the fan mounting holes were slightly off, but they were close enough that i could still mount the fan. 5. I had a half bad HIP4081A chip. But, fortunately i had 3 “extra”. 6. to get it to turn in one direction or the other each HIP4081A input must be grounded, so my arduino PWM code was “backwards”, so to speak…
BUT, IT WORKED!!!!!! I used general diodes for the charge pump circuit, random capacitors for the power regulation, 22N50 mosfets that i got (about 100) in an Electronic Goldmine surprise box. Those surprise boxes were well worth it just for the mosfets!!!! This revision works instead of shorting out, since i fixed the p-channel mixup earlier, which is a relief. It felt good to finally
finish this project. get a somewhat working prototype. It’s technically not finished, but it’s oh so close. Just needs a little redesigning, an opamp, and someone to program code for it.
I hope this homemade speed controller can help cut costs for FIRST Robotics students (on personal robots), so they dont have to buy expensive speed controllers for summer projects, or other hobbyists in autonomous robot competitions. I estimate that you can buy the boards for about ~$60, and the parts for ~20 without scrounging. But, you usually get 2 copies from batchpcb, so the “real price” is about $50 which is at least half the price of the IFI/VEX controllers.
The design could use a few little improvements. I’m still annoyed at the tiny solder pads that eagle cad produces, it’s hard to solder on the boards. http://forums.adafruit.com/viewtopic.php?f=25&t=13885