Subject: fried thermistor
By: tim (IP: 192.250.34.*)
Written on: 06-03-2006 14:52

I did see this question before, but didn't see any answers. I built the temp control circuit, and was running no problem using a pc power supply, but due to issues trying to keep the ps running out of the pc (needing load, etc) I thought I would use a 1000mA Radio shack 12v power supply instead. Within about 1min the thermistor smoked, went red and fried. Any reason this would happen? Want to try again.
Btw Thermistors are readily available from Mouser electronics on line for anyone having a hard time locating them.

By: Tillmann (IP: 146.140.7.*)
Written on: 06-03-2006 15:14


are you sure you used a 10K Ohm (that is, 10000 Ohm) thermistor as specified, and not a 10 Ohm unit?

I really don't see how a 10K thermistor could possibly fry with just 12V applied.

By: tim (IP: 24.63.20.*)
Written on: 07-03-2006 03:13

yes, i verified the thermistor. could it be that I fried the transistor, or pot previously, and that could cause the therm to be exposed to excessive amperage?
By: Tim (IP: 192.250.34.*)
Written on: 07-03-2006 21:58

I checked the voltage out of the Radio Shack dc adaptor, and it looked to be putting out more like 30v than 12. Could this be the problem. I did notice the fan seemed to really be cranking fast when it was connected before the therm burnt out.
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