Where to find a thermistor?

Years ago I had a really nice long two-pin thermistor that came with my PIII 500 MMX

I used that for a long time in various systems as a temperature probe for my CPU.

I can't seem to find it now after all this time and I've looked on ebay to no avail (most seem to be industrial types?). Is there anyplace I can get one of these cheaply? Anybody with a fan control/temp panel that has an extra?

Thanks!

i think most people have gotten away from them just for the fact that they have little use these days on processors since all modern processors can now read the temps internally.. which the pIII couldnt.. they are still around though.. i have one on my xclios case for the internal case temp..

sirmonkey1985 said:

i think most people have gotten away from them just for the fact that they have little use these days on processors since all modern processors can now read the temps internally.. which the pIII couldnt.. they are still around though.. i have one on my xclios case for the internal case temp..

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I just like them for an external LCD temperature monitor I have. Accuracy is not that important. Just a roundabout number I can see.

your best bet is to search a place like digikey.com or other similar electronic components sites and find a thermsistor that is a close match....

Radio shack used to have them as a component, likely a 10K NTC (negative temp cofficient) is what you need. You would have to solder longer wires to the leads.

or

http://www.thermaltakestore.com/thermal-probe.html

You need to know exactly what resistance you need, don't just order a 10k and think that it's "likely" to work. Go to Digikey and just search for "thermistor", there are over 2000 NTC listed ranging from 1 to 1.4M ohms. They are rated at the resistance at 25c so you really do need to know exactly what yours is.

The 10K is almost standard

There is a high probability the Tt one will work.

However as boshuter points out there is a risk, it will not damage anything, temp reading will just be way off or not work at all and in that case do not leave it connected.

If the 10K does not work try a 1K as that is the next most common value.

BillParrish said:

Radio shack used to have them as a component, likely a 10K NTC (negative temp cofficient) is what you need. You would have to solder longer wires to the leads.

or

http://www.thermaltakestore.com/thermal-probe.html

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Thanks a lot a Bill. I do have one very short thermistor that came with an HDD caddy for HDD temperature reading. Is it possible to solder extensions to these? I thought they were very sensitive to changes in resistance?

I would buy the thermaltake one but they charged about $25 shipping and brokerage to ship one single thermistor to Canada since they use UPS exclusively instead of USPS lettermail!

Spare-Flair said:

Thanks a lot a Bill. I do have one very short thermistor that came with an HDD caddy for HDD temperature reading. Is it possible to solder extensions to these? I thought they were very sensitive to changes in resistance?

I would buy the thermaltake one but they charged about $25 shipping and brokerage to ship one single thermistor to Canada since they use UPS exclusively instead of USPS lettermail!

Click to expand...

Holy Crap, no I would not pay that either.

Yes, but adding a foot or so of wire should not throw it off much. It would be important to put a heat sink between where you are soldering and the thermister itself, an alligator clip would do on the thermistor side of the joint and cover with heatshrink where you had to bare the extra wire so the clip could contact bare wire for heat conduction. Trying to say you need to protect the thermistor from the heat of soldering by using anything metal you can find to conduct heat away from the thermisor by placing it on the bare wire between where you are soldering the the thermistor itself. (sorry if over explaining).

Some of the temp monitors have a adjustment. Or if you just want to test for accuracy (most are a couple of degrees off anyway) look up "ice bath". Basically you take advantage of the fact that ice melts at exactly 32F or 0C at sea level . So you take a stryofoam cup and fill mostly with ice (crushed ice even better) and add water and stirr for a few minutes so a nice even thermal profile is established and dunk in your thermistor (coat with nail polish if raw thermistor without tape ) and keep stirring gently. You should get a 0C reading or close. Again the thermisior is pretty accurate , typically 1 deg C but the electronics that reads the resisitance and converts it to a digital readout are prone to couple of deg error unless it is a really high dollar one. Unfortunatley no easy way to adjust but if you know what the error is you just do it in your head.

http://www.thermometricscorp.com/icepoincal.html

good news is it can be reading low as opposed to high so adding length to the lead wire can be used to adjust it (finicky bit of work but it can be done).

Another idea ( I am looking at NCIX ) is like the one you have, it might be easier to buy a fan or something that has a lead and steal it.

eh not finding anything cheap on NCIX but I think you got a good start on solving your prob. Happy Halloween.