Small AC motor speed control options?

[julianf]

I know so very little about motors...

I have a 230v fan, which i want to control the speed of. Its a small unit, maybe 5" dia.


I looked on ebay for PWM controllers, but got things like this -

...which, even (or maybe because) of my lack of knowledge, really does not look like it could be a PWM unit?

ebay link -

http://www.ebay.co.uk/itm/271796867670


Id like a cheap and easy approach.


This is for a bit of kitchen equipment that has a much larger airflow than needed, and replacing the entire fan assembly will probably be more bother than its worth.

Id rather not use a rheostat / dimmer etc. as i suspect the fan will just stall at low speed?

But, again, i know surprisingly little about motors!

 

[rtbcomp]

That looks like an SCR speed controller.

The only way to control the speed of an AC induction motor is to vary the frequency of the supply. PWM & SCR controllers are for universal (ie those with a commutator) motors. These are found in drills, washing machines, vacuum cleaners &c.

Some devices such as desk fans have multiple windings which you select with a switch.

 

[66-V8]

http://www.growell.co.uk/variispeed-fan-controller.html

 

[julianf]

Ill take a photo of the motor - it was not clear to me what the design was.

 

[Robotstar5]

A few here to look at.

 

[rtbcomp]

^^ They're all for universal motors, not induction motors.