Build yourself a temperature control with the following features -Temperature can be adjusted by the user. The desired temperature can be adjusted over a wide range, so the control is suitable both for regulating case temperature and CPU temperature. Fans are switched off if the temperature is low enough and several fans can be controlled with just one sensor and temperature control.
It consists of just three electronic parts!
A MOSFET Power transistor (N-Channel)
A 10K spindle trimming potentiometer,
A 10K NTC temperature sensor.
All of these are standard, easy-to-get parts.
The MOSFET can be just about any N-channel Power MOSFET, as long as it can handle the 12 V voltage and the amperes the fan requires. Even the cheapest Power MOSFETs in the $1 area can usally handle over 50 V and over 10 amperes, so they will be by far sufficient for this circuit. We used an IRFZ24N MOSFET. If you’re in the US, you can use an IFR510 Power MOSFET. The pinout of Power MOSFETs is standardized, as you can see on the image. It is very unlikely that the MOSFET you buy has a different pinout, unless you get a really exotic one.
The spindle trimming potentiometer should be a 10K type. If you cannot get a 10 K unit, 20 K or 25 K will also do. However, this pot is rather large and bulky, a spindle trimming potentiometer is really the more elegant (and also cheaper) solution. Finally, for the NTC thermistor, get the cheapest 10K NTC you can get. It doesn’t matter if it has a high tolerance. You can also use the flat thermistors for CPU monitoring that ship with some motherboards.
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