PT100 Based Temperature Controller with PIC16f877

mrpicing · Joined: 22 Oct 2005 Posts: 20

hello every body!
i want to build a temperature Controller (Range is 100 C to 600 C).
i never used PT100. is it better for this or i should try any thermocouple?
Have any body done it?
have any code suggestion and hardware tip?
THanks.
Keep Picing...

Ttelmah · Guest

What accuracy do you need?.
For both PT100 sensors, and thermocouples, the 'work', is in linearising the sensor. Fortunately, the linearisation recommended in ITS-90, for the PT100, is relatively easy, above 0C. However, if you want better than a few degrees accuracy over this sort of range, things are going to get reasonably hard. You will need to consider careful scaling, to get the output to match the input range of the ADC, and calibrating at (at least) one point, to compensate for errors in the resistors, cables, offset errors in the op-amp etc..
PT100, is a good choice for this.
For a thermocouple, you might want to consider external linearisation, in the amplifier circuit.

Best Wishes

SherpaDoug · Joined: 07 Sep 2003 Posts: 1640 Location: Cape Cod Mass USA

For a PT100 sensor you will need a high gain stable bridge. For a thermocouple you will need a compensation circuit. Both take some analog circuit skill to do accurately. Look at the data sheet of the Analog Devices AD594 for a taste of how to use a thermocouple.

Tell us more about your application and we can give more specific advice.
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