Yesterday, I tested a peltier thermoelectric cooler ghett-rigged onto my telescope CCD camera (pic attached) and was pleased with the results, so I want to make a more permanent/user friendly solution. Besides some obvious mechanical and thermodynamic needs, I also need a controller. I did some very quick gooling and found that there are temperature controllers in the $300 range that would work, but I don't want to pay that much. Dew heater controllers could be useful for the Peltier control itself (or not...se below), but cost $110. http://www.thousandoaksoptical.com/dew.html I don't have a data sheet for the peltier, but I *think* it is rated at 60W at 12V, like this one: https://www.amazon.com/TEC1-12706-Thermoelectric-Peltier-Cooler-Volt/dp/B002UQQ3Q2/ref=pd_cp_e_1 If I ever use a car battery or other not-really 12V source, I could get 13.5V and about 5.5A, so I need something that is rated for at least 6A. I'm thinking that automatic control would be too expensive to buy and too difficult to make (but I'm open to it....), besides which I'm always monitoring my stuff anyway, so I'm ok with just watching temps and controlling output with potentiometers. So. Fan control should be easy - I can just do that with a potentiometer, I assume (not sure what size...). Or just buy a computer fan speed controller for <$10. Peltier control is more difficult. Many I've seen use pluse width modulation and I've seen fan controllers work that way too. How hard is it to make a circuit to do that? Can I easily make one that can handle 6A? Could I make it do active temperature control? I have a dew heater that uses pulse width modulation, but when I tested it on a fan, the pulses were much too wide for my taste. I can't have the fan going zero to full speed and back for 5 seconds at a time, every 10 seconds. And I would think the peltier would be better off doing a constant voltage instead of pulses (though I don't really know that). One other possibility: I'm usng a PC power supply for this, so I have both 12V and 5V available. If life gets too difficult, I can just do a high/low setting on the peltier and make finer adjustments with the fan speed control. Opinions?