I recently found a Permanent Magnet 90vdc motor, 2.5hp, 18Amps. It has simply two wires for voltage (red/black) and two for thermal breaker circuit i believe (blue/blue). It came out of an old treadmill, and was run with an MC-60 motor control board. The problem is, the controller is shot and I really don't feel like wasting a ton of time analyzing what could be wrong with that old circuit being that I don't have the equipment here at home.
My Intent:
To build as simple of a control circuit as possible, giving me basic on/off and a fair amount of speed control. Once I have the speed control I'm looking for I'm going to gear it down to provide a more consistent speed/torque to drive a pottery wheel. If I have to I might get into the whole op-amp/servo-loop for consistent speeds but hoping gearing and flywheel will help with possible speed changes due to weight/load.
Can I use something as simple as the simple 555/mosfet circuit below, obviously scaling up the bridge and mosfet to handle ~30-40 amps or so?
Or should I try to isolate the power supply circuitry from the original circuit, and drive it through the opto via something like my netduino? Thus eliminating all the SoftStart/CurrentLimit/Signal circuitry that is just not necessary to me at this point.
I'd love to hear any criticism/references/possible solutions.
Before you worry too much about giving advice, I do have a good amount of experience with both AC mains and digital electronics. I was a carpenter wiring breaker boxes for 5 years, and now currently build/repair circuits. Where I'm coming short is understanding how to safely connect/isolate the two and drive such a large motor. I've handled smaller ~12v motors but nothing like this. Plus I'm actually testing all of my circuits digitally via MultiSim prior to actually building anything, because I know this isn't one of those "well lets see what this does" type of situations. I'd like to not fry my motor, and keep my eyebrows. :)
Thanks in advance!
