thermo switch / control

[moe]

would like suggestions on using some type of thermo switch to cool a 2 meter radio heat sink.
I have some 12 volt 40mm x 40mm cooling fans that I would like to use to help cool the heat sink
but don't want them running all the time.
Thanks for any help
Moe

[sghioto]

A simple thermo switch like the one in this photo might work. Check out Amazon.com they have a bunch listed with all kinds of temperature ranges.

Steve G

[Externet]

You can canibalize a defunct/discarded PC power supply and salvage its fan and control circuit with thermistor.
Most modern supplies have variable fanning controlled by temperature, with a circuit board independent from its main board. And it is 12VDC. And nearly $0. And will work only when hot. And quiet.

[dacflyer]

Externet >> that fan control.. is it just on and off or is it variable ??

[Externet]

Variable speed. I have collected/salvaged several of those boards with a thermistor from inside PC supplies, all about 1" x 1" that feed the fan from whisper quiet to full speed.

[dacflyer]

thanks,, i'll start digging in the dumpsters for them

[moe]

thanks for the tips
Moe

[haklesup]

you can also find some fan controls in a computer store. Most of these work with the 3 wire fans and some have thermocouples and indicators etc. There is a range of features you can choose from. I searched on "PC Fan Controller" and found many from $8 to $100

The thermostat would be the cheapest and smallest way if you don't care about settability.

[dacflyer]

i dug into about 6 SMP's and only 1 of them had that lil fan control board with the thermister.
i tested it out, and it is only a 2 speed controller, not variable speed..
it turns on low, then when it gets hot, it kicks into high gear, til it cools off.

i'd like to find a circuit that would be a true variable speed control..adjustable of course..