Motor Speed Control


In Universar motor brush washer and AC. I want to control the speed. There are 4 speeds. The circuit for speed change is this:

I know if I have done well. With a PIC I control the optocouplers, only four speeds.

Any suggestions are valid.


The circuit for speed change is this:

I can’t see anything


The circuit lacks mains supply and load, but lets assume that they are in the obvious place.

This is basically the standard DIAC/TRIAC circuit with 2 opto-coupler switched resistances that can be selected, allowing 4 different speed settings. Seems plausible.

Was there a question?

One observation: be safe with mains, make sure the circuitry is double-insulated and physically cannot be touched when live or testing... Observe good PCB trace clearances between HV and LV (ie lots of clearance, slots under the optoisolators if poss).