Here is my motor controller design for my Alco RS3. I basically gutted the entire thing and rewired it using a Pololu 18V7 simple motor controller. I’ll combine that with a 2.4Ghz radio and my home brew sound card and it should be really cool. Not quite finished with it but it’s coming out quite nicely. I plan on wiring up a battery pack using C sized 3500mah NiMh batteries for motive power.
Actually, I think I’ve changed my mind on the wire harness a bit. I was going to use the Pololu Motor controller in the traditional way, ie, center joystick is off, all the way up is forward max, all the way back is reverse max. But after some contemplation, and getting the R/C decoder to work, I think I’m going to put a mosfet and DPDT power relay in play here. I’ll use one channel to flip the direction back and forth and then I can utilize the entire range of the joystick (a knob in the case of my hacked transmitter box) for applying power.