120vac fan motor controller

[mhefler]

I'm currently trying to figure out the best way to control a single phase 120vac fan for my smoker, I'm looking to be able to slow it down without over heating it. I have played with a few different opto-coupler designs but have bad no luck, if I use something w/out zero cross detection the speed is all over the place, and I have had bad luck with designs with zero cross. is there an inexpensive solution to this problem? I'm trying to have complete control of my smoker through an arduino and this is my last obstacle.

[adafruit_support_bill]

Is it an induction motor or a universal motor? Induction motor speeds are relative to line frequency and are not easily controlled.

[easternstargeek]

Your fan is probably a shaded-pole induction motor. It's not really possible to control the speed and still get decent performance.

Consider for a moment what you're trying to accomplish- Modulating the air flow through the smoker.

Have you considered just letting the fan run normally, but fashion some kind of variable damper that you can open and close with a RC Hobby Servo? If you fashion a damper out of two flat plates with parallel slots- one fixed and one moveable, you can go from full open to full closed with a plate displacement equal to the distance between slots. If heat is an issue, you can fashion a pushrod to couple the servo horn to the damper slide, either through a heatshield plate, or just by distance to keep the servo from overheating.

[mhefler]

the fan is a shaded-pole induction motor.

[adafruit_support_bill]

The practical options then would be some kind of damper to control the air-flow as suggested above, or to replace the fan with a DC fan & PWM speed control.