> Russel thank you for the answer.  I will do a search for Peltier an=
d
> environmental chamber and see what comes up and go from there.  I n=
eed
> something that I can set between -25=B0C to +75=B0C (-13=B0F to +16=
7=B0F) plus
> or
> minus 5=B0C, I don't need a very precise instrument.

That's liable to be rather too low for a simple Peltier cooler. You c=
an get
multi stage units but cooling capacity drops and price rises alarming=
ly.

If I was wanting to do this "on the cheap" I'd consider using eg dry =
ice as
a cooling medium. You could blow air through a dry ice chamber at a v=
ariable
rate to achieve a variable rate stream of cold air and use a simple
electronic temperature sensor to control fan speed. A few polystyrene
"chilly bins" and some polystyrene insulation should suffice. On the =
heating
side you are unlikely to have much trouble. Light bulbs or power resi=
stors
of some sort should suffice as heaters for small boxes. Or a fan heat=
er.



        Russell McMahon

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