landyacht318 wrote:
I have one 120Mm delta fan which is ridiculously powerful at 252CFM and at about 50 watts, but it cannot be slowed below about 35 watts via PWM or voltage control, or it just shuts down. Much too loud and powerful for normal use, and its impeller will easily chop off a fingertip.
Nidec and Delta both make some awesome fans.
If you're ever in the market for a do-over on a speed controlled fan, the 4-pin "PWM" type are very easy to drive with a microcontroller or 555 timer circuit. You don't chop the supply voltage, as that messes up the brushless controller.
The 4th wire is a pwm input (3rd wire being a hall-effect switch open-drain for tachometer). You feed it a ~100hz pwm signal to vary the speed, or connect it to ground for minimum speed. The brushless controller will sync with the pwm input and resist stalling, vs pwm of the main dc input.
