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illusionist wrote:Well... I got a meat thermometer, took it apart (or should I say broke it apart), and to my disappointment found that it had a curly bimetallic strip inside. It is about 4 inches long, pretty thin, and curled up like a spring. I'll pass some current through it later, but has anyone else found success with these? Is there any way for me to make use of this thing?
Edit: I ran electricity through it and it started to make smoke... I'm guessing that's a bad thing... Oh, by the way Primate, it was a Acu-rite thermometer.

If you're using an Acu-Rite meat thermometer, maybe it'll work better. The outdoor dial Acu-Rite I had wasn't actually a bimetallic strip--it was just a plain old metal curl that required serious heat to move.

You might have better luck with a two inch strip. Unbend it, then curl it into a 90-degree arc. Run current through it, and it should uncurl. (Smoking isn't necessarily bad, just be careful!)

Would you be able to run a current through a bimetallic coil to have it heat up, then break the current and have it cool down? Or is a nichrome wire necessary?

I've heard of a team doing running a low voltage current through a coil, but it took maybe 15 seconds for it to cool down.

Ninja, what my team and many other teams have done is to have a 6V battery hooked up to the bimetallic coil. It is always running, and when a switch is hit, it turns of the current going to the coil. The coil then cools down and uncurls.
As to the time, I used a rather thin coil, so it cools down in about 9 seconds. Depends on the type of coil and its thickness
Btw, you want to use the big square 6V lantern batteries, as they last much longer.

illusionist wrote:Ninja, what my team and many other teams have done is to have a 6V battery hooked up to the bimetallic coil. It is always running, and when a switch is hit, it turns of the current going to the coil. The coil then cools down and uncurls.
As to the time, I used a rather thin coil, so it cools down in about 9 seconds. Depends on the type of coil and its thickness
Btw, you want to use the big square 6V lantern batteries, as they last much longer.

Ok I think I'll do that. How long on average does it take for the charge to start fading?

buzzbuzz wrote:I've heard of a team doing running a low voltage current through a coil, but it took maybe 15 seconds for it to cool down.

Yeah, today I was testing with different voltages, and it cooled down a lot slower than I expected.

Shooting any amount of water willing nearly instantly cooling the strip (a syringe or a pump would do great, if you're willing to wire something)

austinfhs wrote:Shooting any amount of water willing nearly instantly cooling the strip (a syringe or a pump would do great, if you're willing to wire something)

Thanks for the tip, I tried it out and it worked extremely well. Only thing is, how would you recommend 'wiring something'?

Our system was basically a three way switch. The nichrome is left on, before you begin your tasks. Then you hit the three way switch, which will turn off the nichrome and simultaneously turn on the pump to spray water on the bimetallic strip. You'll have to make a pool and shield so that water doesn't splash everywhere, but it'll fairly efficient if you can get everything to work. The three way switch is kinda fancy, you could pull it off by simply turning on the pump. Unfortunately it's kind of hard to attach the nichrome to the bimetallic strip and then get the strip to trigger the next task.

That sounds pretty cool. Could you post a pic of that setup sometime?