>-----Original Message-----
>From: William Chops Westfield [mailto:westfw@MAC.COM]=20
>Sent: 16 January 2004 11:20
>To: PICLIST@MITVMA.MIT.EDU
>Subject: Re: [EE:] About test boxes (hot and cold)
>
>
>On Friday, Jan 16, 2004, at 02:43 US/Pacific, =D6mer Yalh=FD wrote:
>
>> Russel thank you for the answer.  I will do a search for Peltier and=20
>> environmental chamber and see what comes up and go from=20
>there.  I need=20
>> something that I can set between -25=B0C to +75=B0C (-13=B0F to=20
>+167=B0F) plus=20
>> or minus 5=B0C, I don't need a very precise instrument.
>
>the January Circuit Cellar Ink magazine had a project where=20
>the author had converted a cheap (relatively speaking) peltier=20
>drink cooler into a CPU-controlled temperature chamber.  It=20
>was quite a reasonable=20
>article.
>I believe they only got 8 to 60C out of it, though.  Peltiers=20
>are not very efficient coolers, so it's hard to get very low=20
>temps, especially if whatever you're cooling is generating any heat...
>
>Used a PIC, too, I think.
>
>BillW

Unfortunately the author decided to use thermostatic control of the TEC,
which is definitely not recommended.  The constant thermal cycling of the
TEC will cause premature failure.

A switching or linear controller is prefered, and coupled with a decent PID
controller will give improved temperature stability over a simple
thermostat.

Regards

Mike




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