-------- In message <F57B1617EE984B10AAD5379A2402DFE6@D77M7BF1>, "Dave M" writes:
>I was intrigued by the use of a Peltier chamber to control >the temperature [...] It's a very obvious idea, but it runs into one of the widely unknown footnotes about peltiers: Don't feed them AC. The thermal/mechanical stress when you change direction of the current significantly shortens their life. I should add that I have not found any studies which say to what degree this depends on the magnitude of the current, so an oven balancing around a couple of mA may not be a problem, but switching polarity on several amps will be. One complication is the difference in directional efficiency: The warm side receives about 4 times as much energy as is removed from the cold side. Unless you electrically compensate for this, your PID will be *really* confused. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [email protected] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
