[vmelkon]

I had forgotten about peltier for a long time. It was such a weak event that it seemed useless. I had a copper/aluminum contact and heated it and it produced minute amount of current. That was over 10 years ago.

Ok, so now we have Bismuth Telluride peltier devices that can drop temperature by 50 C or something. There isn't much technical details about them. How low can you go?
I saw one post on this forum from a guy who thinks -50 C. Obviously, you need a cascade system to do that. Perhaps if you had a freezer at -20 C and put your tiny peltier in it, the cold side could theoretically drop by 60 which give -80C, enough to freeze CO2.

[billnotgatez]

Would this be any more efficient than a heat pump?

[vmelkon]

No, they are quite inefficient compared to heat pumps. The advantage is that anyone can buy them, such as myself.

[billnotgatez]

Bismuth Telluride is easy to get?

[skyjumper]

http://unitednuclear.com/index.php?main_page=product_info&cPath=27_75&products_id=455

$29

[billnotgatez]

Nice find!

Is there a peltier wire we could wrap around a test tube available?

[vmelkon]

If you want to cool a test tube, you could use a drill to make a hole in a aluminum block and cool the entire block with a peltier.
Now I had a second guy say that -60 C might be achievable. hmmm, not so bad but I would like lower.

[billnotgatez]

I would think that drilling a hole would disrupt the different metal interface. But, i could see a block being built that had a space for a test tube in it.

[skyjumper]

You could simply take a couple blocks of aluminum and attach one to each side of the cooler, drill a hole in each block and have a combo test tube cooler and warmer.

[vmelkon]

Hi,
I'm just reviving my old thread because I did my little experiment with one of these peltier devices.
I made a video showing that it gets cold enough to freeze mercury.

http://www.youtube.com/watch?v=7KIRIgFfOhw

[Grundalizer]

You can get them off ebay for $3-$8