PWM fan speed control with a 12F683

[AvionicsMaster1]

I didn't have a coil so I tried the cap across the motor and voila!

Thanks.

I still can't get the fan to do three speed steps it's either on or off. Any ideas?

[sayzer]

Not all fans can be controlled by PWM.

Try your fan directly with 5V power supply, and see if it runs.
Most likely, it won't run at 5V.
Increase the voltage and see at what voltage it will start running.

If it starts running at around say 10V ~ 11V, then you will have to change your fan, which most probably is controlled by an internal electronic controller.

Try your circuit with a simple traditional DC brushed motor and see if your PWM works.

[AvionicsMaster1]

You are so smrt. I mean smart.

I assumed a DC fan would run slower at half of rated voltage and slower still at quarter of rated voltage. When I tried your test on my test fan, sure enough it wouldn't run on 8 volts and labored significantly on 10.

I've yet to try the PWM on a real DC fan without a speed controller but I'm sure it will work just fine.

Thanks.

[Demon]

Moved from Schematics.

Robert