Basically we could zero out and measure the change in volts per degree C from there. Applying a known temperature such as immersing the sensor in ice water would be a simple if inconvenient way to establish a known reference temperature. Knowing the temperature coefficient of a sensor is only half the equation, we also need to nail down the zero point, meaning that we establish a calibrated reference point.
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What I will cover is a reliable and precise way to read from these probes, seen in the video below and the remainder of the post after the break.ĭifferent thermocouples sensors have a different temperature coefficients meaning that they will generate different amounts of voltage for the same change in temperature, usually specified in volts per degree of Celsius (v/◦C). If you’re not already familiar with the construction of these probes you can find an informative write-up on thermocouples and the different types on the Wikipedia page and you might also want to check out the Analog Devices app note if you would like to know more. In the video I don’t really talk much about the thermocouples themselves other than the type I see most of the time which is type K. I thought it was an ideal example of an analog application where some gain and some “gain helper” were needed to accomplish our useful little application of amplifying a thermocouple probe. While researching “Zero Drift Amplifiers” as a follow-up to my video on Instrumentation Amplifiers I noticed the little schematic the front page of the LTC1049 datasheet which is shown here. Linear Technology LTC 1049 Low Power Zero-Drift Operational Amplifier But to make that measurement you need an amplifier circuit designed for the thermocouple being used.
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The effects of temperature change on dissimilar metals produces a measurable voltage. A Thermocouple is a terrific way to measure temperature.