temp switch

I am looking for the schematic or diagram for a simple temp switch using a thermistor. something that i can kick a couple of 3 inch fans on to cool radios in a console. any ideas??
TNX Jim W7OWC

Hi,

I have built this circuit which works like a dream as they automatically alter the speed according to the ambient temperature and will switch off when not needed. The circuit will drive 4 or 5, 3 inch 12V fans drawing about 200mA each.

**broken link removed**

Cheers
Andrew

PS: The circuit does not use thermistors but diodes which rely on ambient rather than actual temperature. By placing the sensing diodes close to the equpment you can sense the temperature in that manner.