Sounds like a great idea I thought, so I bought one off Amazon and gave it a whirl.
It came in yesterday. When I hook up a light bulb to it, I do get a dimming result of the bulb... So I know the SCR is working.
Then I hook the SCR up to the BR, then to my motor. The motor spins, and the SCR controls the speed, but I'm getting major sparking from the back of the motor.
My motor has 4 wires coming out of it. 2 blues, 1 red and 1 black. I'm hooking the red and black to the BR just like in this video:
https://www.youtube.com/watch?v=_NmAFZMAfH8&app=desktop
When I switch back to controlling it with the factory treadmill speed controller, I don't get any sparking out of the back. Any ideas as to why I'm getting the sparking?
I know you have a 2x72 belt grinder with a treadmill motor, what did you use to control the speed?