Electronic – used to control AC motor speed

motor controller

This is a AC 220v 60W 0.2A fan I recently bought to replace my old bathroom vent that gave up some time ago. The problem is that the new one doesn't come with a built in speed controller like the old did, so the fan is running really loud. The people at the store tell me to go to another store to buy a speed controller but I have only found dimmers or expensive industrial speed controllers. I studied electronics some years ago and have been looking for a way to build such a speed controller, the question is how. My first guess is to control the speed by reducing the watt or amp. Any help would be welcome.

Some schematics that came with the unit (The instructions are in German):


Best Answer

For an AC motor, you can reduce the voltage to reduce the speed. As a quick hack, you could try running it off 120 V AC; if that speed is good, you're done.

Otherwise, you could try a triac, which chops the voltage for part of each AC cycle, making the average voltage lower, or you could use a variable transformer, like this: http://www.electroniccity.com/shopping/pricelist.asp?prid=1147