I need to source a very small thermal switch that would fit beside a peltier and open at approx 50 C.

This is to prevent someone from getting a burn. I was thinking of the small battery cut offs but I do not know if they reset once opened.  The smaller the better as it would be ideal if it was flush with the peltier. I would like to wire it to the power source as a simple mechanical thermostat. 
Power supply ranges from 5V, 500ma to 13V, 1A.
It needs to be simple as there is no logic board.



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There are these type


Which are pretty simple, but may need a relay to handle the current.

There are these


This type is very small, but requires a small relay to switch the load.
messyworkbench (author) 7 years ago
This is for my son's science fair project. He is making a USB beverage cooler/heater. Current designs heat/cool air inside an insulated container but at a maximum 2.5 watts from a USB they are pretty ineffective.
He will have the pop can/cup sit directly on the peltier, which is on top of a heat sink, which is on top of a fan, which sits on a fan guard. Even at 2.5 watts this can actually cool down a warm pop and heat up a cup of coffee. An on-off-on rocker switch is used to reverse the polarity to the peltier to make it heat or cool down beverages. I would like to see him have some sort of safety feature. The link to Selco is much appreciated, I prefer to support those that support this site. The UP72 looks like what he needs but I do not know if this would reset by itself for numerous cycles or is it a "one shot" as with a thermal fuse, or limited switch cycle life? I assume you order them with the temperature range you want and they are preset for you?
Usually a switch such as steveastrouk suggested is used but they are too bulky.
Thank you very much for all of your help, I appreciaete your answers and I believe I am getting close to what is needed.
The second item I suggested isVERY small, and we use them in our own Peltier systems.

messyworkbench (author)  steveastrouk7 years ago
Man, I should slow down sometimes. Yes, that looks very promising. Funny that they are/were made in Canada.
Could I attach the tab to the peltier with epoxy and have the heat transfered to the device by the tab or is the tab used for fastening?
I would prefer not to have to put on a section of copper to distribute the heat as we have to keep the device light. When in use it will be attached to pop can/coffee cup.

Thank you again, this is wonderful help.

The cell will love you for mounting it on a metal plate.

lemonie7 years ago

kelseymh7 years ago
Thermal cutoffs (also called thermal fuses) are single use devices. They're wired in for personnel and equipment safety. It sounds like you're looking for something like a resettable circuit breaker which can be triggered on temperature.

Ah, ha! Do a Google search for "thermal circuit breaker". One of the sponsored links (blech) is Selco Products. Check out their "thermal protectors" line, which I think is what you want.

Once you've got a useful set of keywords and/or part numbers, you can try searching Google, or other electronics suppliers directly, to get a good price.