PWM Temperature Controller

Hello Everyone,

I’m sorry if there is already a forum for this; I searched around but couldn’t find anything.
I need some help - I am looking for a board that can operate from 4C-43C, has DC input <=12V, can output up to 6.1A, and is as small as possible. I’ve found a couple of these already set up to do this, but they’re well over $100 U.S. I would like to stay below $30 if possible, otherwise it will become infeasible due to the cost. I’m going to use the board to power a thermoelectric cooler to produce water so I need to be able to regulate the temperature so the cold side doesn’t freeze, but get’s cold enough to produce condensation (any good ideas on how to do that?). I also need the controller to be able to receive two input temps - one for overheating and one for freezing. It would also be nice to be able to hook up something like a mercury sensor so it would shut off the system if it fell over.
I’m a new guy, so I appreciate any and all help you can offer me.

Thanks in advance!

One word got my attention: mercury. That is toxic. Some simple tilt sensors use a metal ball and a few contacts. You could also buy an accelerometer for a few dollars on Ebay.

Did you look at the Sparkfun website for motor drivers ? They have a nice selection of motor driver boards.

I don't know the range of the 'hot' side and I don't know how accurate you want the 'cold' side. You could use the DS18B20 (-55 to +125 Celsius), or a thermo-couple, or a NTC, or a diode. The temparature sensor should be connected very well to the surface. If it falls off, the temperature could get out of control.

For condensation, perhaps 1 to 5 degrees Celsius will do. An accuracy of 0.5 or 1 degree should be good enough.

Give more details on what your design problems are - why 43C? I take it that you are controlling a thermoelectric cooler for distillation. I'd advise you to try to build in the thermal control into the structure of the design as much as possible. How do you even know that the TC cooler is going to overwhelm your steam source and "ice up?" Younare not giving enough information to allow me to advise you.

Erdin,

Thank you for the constructive comments. I'll definitely heed the sensor thought, I don't know why I didn't think about that. I have not searched the SparkFun website, but will definitely give it a shot. I'll look into the temp sensor as well, that is more than precise enough for what I need.

Lockinamp,

43C because it's going to be in a container that will be exposed to temperatures that high. I'm using the thermoelectric cooler as a dehumidifer, not as a distiller. As I mentioned, I'm a new guy. If there is more information that you would like so you could help, please just let me know what you want and I'll do my best to get it all for you.

Thanks in advance.