I would to make variable speed control based on temperature of my AV rack. I currently set it manually with a old school rotating lamp dimmer (incandescent). Anyone knows if some of those plug in lamp dimmers may work with a fan?
Unfortunately, you can’t use a lamp dimmer with a variable speed motor because the physics are different. See the FAQ ( this is a clickable link)
There are some switches specifically for controlling fan motors, including one from GE that is very popular, that will give you low/medium/high if that’s enough. If you want more stages than that, you have to look at something specifically designed for motor control. There are some which are used for window shade motors, but they are usually more expensive than the three stage switches.