Control AC sewing machine speed with an Arduino

Nigel Goodwin said:

He's vastly over complicating it, the circuit for controlling an incandescent lamp or a small universal model is identical. He's talking about controlling large motors accurately, not simple speed control on small motors. Sewing machines, electric drills, vacuum cleaners etc. all use simple phase shift triac or thyristor circuits, just the same as lamps.

Click to expand...

Alright, so is there any risk if I try to wire the module like this if brown is the phase ?

View attachment 122288

DIYO said:

Alright, so is there any risk if I try to wire the module like this if brown is the phase ?

View attachment 122288

Click to expand...

Again, it depends entirely on how the motor is wired. It also doesn't help that there's no circuit for the dimmer module you have - so it's guessing all round.

But assuming the motor is wired directly to the live/phase (inside the unit), and the neutral connection from the motor is connected to the three pin plug for the speed control, and that the output connections on the dimmer are completely isolated from the mains, then it should probably work - but the neutral connections would most like need connecting together.

But it's all guess work, when we've got no details.

Nigel Goodwin said:

It also doesn't help that there's no circuit for the dimmer module you have

Click to expand...

Schematic is here.

Pin out is here.

Datasheet for the triac is **broken link removed**.

Hello,

I had to let this project down for a while but now I'm back at it and I still have no clue on how to control the speed of my sewing machine with an Arduino...
Can anybody help me ?

On the many Arduino forums, search for AC phase control. Some people call this technique AC PWM control, which is not wholly accurate.

AC phase control is similar to PWM, but the timing period is determined by the AC waveform's zero voltage crossings.

If you employ a Triac with a high dv/dt rating, which vendors like Littlefuse call alternistors, you should have absolutely no problem driving an universal motor.

I dont useally get involved in this kinda thing, but here goes:
This guy replaces the potentiometer in a drill speed control with a light dependant resistor, then lights it up with n led driven by one of the analogue o/p's on an arduino, sort of a diy opto isolator, nifty idea.