My existing setup:
- Rae Corporation gear motor (90vdc, 4.5amps, 120rpm, 150 in/lb torque, Part number 6040042). I can't find a datasheet, but it looks a lot like this
- Dart Controls motor controller 15DV1A, (datasheet) which takes in AC main power and runs the motor. Pots on the board control max and min rpm as well as implementing IR compensation.
- the main speedpot shown attached to the 15DV1A relocated to the end of a long cable with connecting it back to the board. I've measured the voltage across this speedpot - it's about 6.5V from Pot-Low to Pot-High, with the Pot-wiper being somewhere in between depending on the pot position. The site says it's a 5k ohm pot.
Here's the question: I would like to control the motor with a raspberry pi - how?
I see a couple of approaches:
#1 Replace the pot:
there are variable resistor ICs, but reading around it seems like they would not handle the current that passes through when the resistance is low.
I've also read that mosfets can be used to create variable voltages, but they are very sensitive and only operate this way over narrow range. Also, it seems like hooking this up is complicated.
digital potentiometer, like this or this. Would this be able to handle the current as a replacement for the pot? If so, this seems like the best approach but how can I wire it so the 6.5v motor control signal is isolated from the RPi?
#2 Control the existing pot:
- I've seen folks use a stepper motor to control a knob, sort of like this. While I appreciate that approach wouldn't modify the existing arrangement at all, I want something smaller and more direct ideally.
#3 Replace the entire Dart Board
- I really don't want to do this, since the board provides some nice features. But if this would be cheaper than either of the above two, I'm listening.