wrote:

Thanks guys...By all accounts there are lots of these in operation
without any major issues such as stalling etc...I'm just keen to
understand how to size in the pot given our local suppliers don't have
a huge range to choose from. They start at 500ohms and up..I can
source a 200ohm one online.


On Nov 16, 8:39�am, "BigWallop"
wrote:
wrote in message

....

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.

Is this any good to you? �http://brewiki.org/StirPlate


200ohm pot with a 220 ohm R in parallel with it would be perfect.


NT