large scale servo hack
 

Looking for some help. What I am trying to do is use an automotive windsheild wiper motor for a servo. Why? Well, its for power steering on my kids powerwheels. I had previously had it radio controlled. It used a gearbox and a speedcontrol for the steering. It gave it full left or full right only. Now I'm trying to make it act like a servo.
My first thought is to use a servo to drive a pair of relays to run the wiper motor. From what I have gathered is that the relays don't shut off fast enough and overlap then burn out. So an "h" bridge is in order. The one commonly used is like 80 bucks. It seems like there should be a cheaper way.
I planned on hooking the potentiometer to the linkage . Any thoughts? I figure the wiper motor will draw around 20 amps/12-18volts.

I know this is a very old post but did you ever make any progress on this? I'm attempting to do the same.

You're right, using relays in a H-bridge array is sketchy because if they don't open fast enough you can short your power supply. But there are ways to get around that. I'm trying to avoid using a transistor bridge and make it work with relays.

-Tony