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Microcontroller Programming » Peltier Cooling Feedback System

February 20, 2012
by TheUnfocusedOne
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Hey all,

Has anyone worked with peltier plates before? I've got a project I'm interested in trying, but I haven't a clue how to get started wiring and running a peltier system. Advice welcome!

February 20, 2012
by 6ofhalfdozen
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Hiya TheUnfocusedOne,

While I haven't yet hooked a peltier up to a nerdkit, I have worked somewhat with them. So here are a few thoughts and items that hopefully will help or at least point you in a direction to start looking for answer.

I don't know how much you know about them, but here is a short blurb. Peltier junctions work on the same phenomena as thermocouples just backwards. I want to say it is called the Seebeck effect, which is when two dissimilar metal junctions are at different temperatures a voltage difference occurs. The peltier, or thermoelectric, effect s somewhat derived from the Seebeck effect. It says that when a current is passed through a junction of two dissimal metals heat is generated on one side of the junction and depleted on the other. The more current is passed, the more heat is generated/depleted to a certain point. But the current and heat both need to flow, which is why all "finished" peltier coolers have heat sinks and fans on them.

Peltiers are really cool, but tend to be power hogs. At least as far as trying to get one to work with nerdkits, the biggest problem is the current draw required is usually measured in amps, not miliamps. We have several we use at work which range from little CPU type coolers +12VDC ~1A up to "Mongo" a 24VDC 15Amp cooler we use for a very special system. I have seen very small ones that run on ~3.3V ~60mA but they are very small and tend to have tiny cooling capacities.

While I haven't messed with any insides of the controllers for peltiers, I believe the smaller ones tend to run off of a pwm based control through a diode/relay/ssr depending on size. Our "mongo" has a serious control box for all that power, and I am not certain how it works and definately have no desire to take a peek!

While I have some peltier stuff on my list of projects yet to do, I haven't done anything yet. My rough idea was to run pwm from the NK out to an ssr for a small-ish peltier. But that is still a decent bit down my project list.

anyhow, hopefully there was some usefull stuff in that ramble.

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