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How do I interface to an old digital meat thermometer probe? It has a stem with a wire and a mini-plug on the end? Answered

The stem is stuck into the meat and is left in the oven. The wire is then brought out of the oven and connected to the display. I would like to replace the display with an AVR micrprocessor, but I do not know, or how to find out, what kind of signal is at the end of the plug. Has anyone played around with these and can share their experience?

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Jayefuu (author)2009-07-03

This website explains well the difference between thermistors, RTDs and thermocouples. Whichever it is, you'll still be able to measure the voltage across it changing with temperature and it will still need to be hooked up to an analogue to digital convertor.

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geeklord (author)2009-07-02

I agree with others, Its probably a thermistor. Try connecting the rings of the mini plug to the probes on a multimeter and see if the resistance changes.

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Jayefuu (author)2009-07-02

At a guess.... the probe probably contains a linear thermistor and is connected to a voltage divider. As the temperature increases, the resistance of the thermistor decreases, lowering the voltage across the thermistor. To change this voltage into an output the display can use, an analogue to digital converter is used to give a distinct set of digital values across a known scale. Someone confirm?

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NachoMahma (author)Jayefuu2009-07-02

. It could be a thermocouple, which produces a mV signal. . Thermistors are sometimes called Resistance Temperature Devices (RTD).

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steveastrouk (author)NachoMahma2009-07-02

An RTD is usually a platinum resistance thermometer.

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