Can anyone guide me on how to control a motor that I have.
It is a 1/60 hp 115v single phase AC motor that pulls .38 amps at full load
It does have a capacitor on it also.
4 Wires from the motor: Blue, Black, Yellow, and Red. I do know how to wire it for forward and reverse.
I want to be able to run it in both directions with Arduino
I do not have to control the speed, but it would be a cool option. But from what I understand a motor with a start capacitor can not be speed controlled?
“AC motor” isn’t a unique description. Is it a universal motor? A shaded-pole induction motor?
A synchronous motor? If this means nothing post photos - include the motor nameplace.
permanent capacitor split phase induction motor.
You can’t vary the speed without a VFD.
A DPDT relay could be used to reverse one of the windings to provide direction change, you’d
probably want a snubber across that winding to reduce arcing at the relay contacts. I’d
suggest controlling the capacitor winding, it will be taking less current anyway.
It may overload the motor to reverse the winding while its running, you may need to turn the motor
before operating that relay. Another relay and snubber needed for on-off control of course…
And “WOW that’s hugely expensive for a hard to control 12W gear motor” - at least it has helical
I got it for $20 off E-bay and it was the exact rpm and torque I needed.
Relay part is easy, I basically have it running of relays now to reverse direction. Any recommendation on a correct snubber to use?
Depends on the inductance of the windings, and the current level. You don’t want it to resonate at mains
frequency, that would be very bad, so a well-damped R-C series snubber is pretty sensible approach.
You have to compromise between the power lost to the R during normal operation and the size of the voltage
spike on switch-off.
I’d start by measuring the AC currents (carefully!) and estimate the coil inductances from that. The basic
equations for RLC circuits aren’t hard to find. Budget perhaps upto 1W for the resistor so losses aren’t
There must be charts of these things on the internet somewhere. The capacitor must be UL approved / mains rated of course.
I found this discussion: