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Unread 07-16-2003, 10:05 AM   #19
wymjym
Cooling Neophyte
 
Join Date: Sep 2002
Location: near Austin
Posts: 96
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Quote:
Originally posted by Broh'kehn
There is a way to create a control system.
The first thing you needs is a pair of operational amplifiers, you can get these at an electronics store, also you need a pair of thermocoples or similar and a few variable resistors.
The op-amps can be tuned to give off a signal when the temperature is higher or lower than a given value. this is then fed into a logic circuit controlling a relay, this switches the peltier on.
Im currently trying to design a logic circuit to allow this to happen but the challenge is to make it switch on at a high value and stop it again at a low value.
Pelts do not live a long life if they are swithced on/off a lot, as you have suggested with relays.
PWM is a better solution, contrary to what was stated earlier.
VPC makes the least expensive units I know of (and have used) to control the pelts based on temperature. TEDistributing has a line of controllers but they are more lab type pieces and expensive.
I have seen some folks that built their own, with great success. So this is a 'green' approach that works and makes sense.
wj
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