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- How to control PC fans with a Pot?
- Markus Stone
June 1, 2005, 11:23 am
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I've got 2 PC fans (12V dc running from a 500mA rated supply). Thing is,
whenever I try to use a pot to control their speed, the pot starts smoking.
This has just got to be possible, but everything I try just smokes the pot.
How can I control the fans with a 1/4 watt pot? do I use a transistor and
use the tranny to control the base current, thereby avoiding the power
Re: How to control PC fans with a Pot?
You're using the wrong method to control the pot.
Use a pulse width modulation system. Jaycar sell a DC motor speed control
kit for about $24. It's an overkill (designed for motors up to 10A), but it
will do the job. The kit number is KC-5225. Or you could use a 555 timer
as a PWM, driving a transistor or a FET.
Use a 3 position switch that switches the following to the fan.
1. 5V and 0V - low
2. 12V and 5V - medium (the fan sees 7V)
3. 12V and 0V - high