T&L Publications

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

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

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.

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

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.

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

thanks for the tips
Moe

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.

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..