Hi All; I am working on a bit of a variable output power supply, and I would like to be able to automatically vary the cooling fan speed for the heat sink. The fan will be a standard computer type; maybe 60 x 60 x 10; less than 2 watts, 12vdc, two wire device. I have seen several types of temp sensors that bolt onto a heat sink, and sends information which is used to vary the fan speed, likely through a PWM type circuit.
But I am wondering if there might be some simple inline device with a resistance of maybe 60-80 ohms at room temp; decreasing to zero or close at around 180-200 F? Anyone know of anything that works like this, and how I could find the right one?
Thanks for any help, Rod