wrote:

Can someone tell how I would size a potentiometer for a circuit to
control a simple 12v fan ( ex pc).

Fan - Roughly 12vdc/ 0.15A/ 1.8Watts

Input Power - Old movile phone charger - 6v upto around 12v DC
depending on model I find in the garage.

Am making a magnetic stir plate and using the fan with a couple of
magnets stuck onto it as the main drive unit

Thanks for your help

Ged.

When the fan gets 6v at 75mA, the resistor drops 6v 75mA (12v psu). R
is then
6/0.075 = 80 ohms. So a 100ohm pot and 12v psu would give you good
control.

75mA x 6v = 0.45 watts, pretty much any pot can handle that.


NT