Measuring Component Temperature (bonus if with built in mp3 player)

On Wed, 20 Dec 2006 00:15:59 GMT, snipped-for-privacy@comic.com (D from BC) Gave us:

The thermocouple is the cheapest, best tool for the everyday consumer.

One needs to insure intimate contact with the test surface.

This means a non adhesive approach as in raw air. Such a setup requires a small tape tent over the probe's active element to keep local air current drafts off of it.

The other is to use a thermal cyanoacrylate or thermal epoxy to attach said probe element.

Infra-red is great, but the operator needs to know the error level of the device as well as how to calculate for emissivity offsets if said device does not include an emissivity adjustment. Depending on the accuracy one needs, as well as one's budget, this solution does work, but requires skill and a good quality IR thermometry instrument.

The IR emissivity of most electronic discreet components vary widely. Surface quality is the main factor for epoxy encapsulated devices. For enamelled or metallic as well.

Shiny surfaces emit more slowly than rough, matte finish surfaces do.

A medical pen thermometer is around $3 and has an accuracy of +/- 0.5 degrees C. That's good enough for me.

Of course if I need to monitor the temp over a long period I'd bit-bang a DS1621 from my serial port and datalog it on my PC. Those air-cond thermostats are quite cheap and fairly accurate to +/- 0.5 degrees. The only problem with the DS1621 is the very slow rise time (the heat needs to penetrate the ceramic IC package). But that's not a problem for long duration monitoring.

You can learn some from CPU of computers.

"D from BC =D0=B4=B5=C0=A3=BA "

Interchangeable thermistors are hard to beat. I think Farnell still stocks +/-0.2C parts and Newark had a +/-0.05C part when I last looked (but it wasn't cheap. Sensitivity is about -4% per degree Celcius, and I've had +/-0.001C ot of them, and the record is around +/-3.5uC.

The calibration curve is a swine - search on Steenhart-Hart - but not difficult in a micro.

A medical pen thermometer is around $3 and has an accuracy of

Of course if I need to monitor the temp over a long period I'd bit-bang a DS1621 from my serial port and datalog it on my PC. Those air- cond thermostats are quite cheap and fairly accurate to +/- 0.5 degrees. The only problem with the DS1621 is the very slow rise time (the heat needs to penetrate the ceramic IC package). But that's not a problem for long duration monitoring.

------------- My first choice is thermocouple due to other postings but... I peeked at eBay for a digital thermometer and did come across the medical pen thermometers like you mentioned above.. It's a respectable suggestion...thanks.. Although... Got a laugh when I saw the "Musical SpongeBob Digital Thermometer". Picture on

If you ever had a problem with coworkers borrowing your test equipment..I think the SpongeBob is a good deterrent :)

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If it is a chip and it really matters, you determine the junction (die) temperature.

The IR temp gun is my favourite. Quick, simple, not terribly accurate, but better than smelling burning skin.

-- Regards,

Adrian Jansen adrianjansen at internode dot on dot net Design Engineer J & K Micro Systems Microcomputer solutions for industrial control Note reply address is invalid, convert address above to machine form.