Dealing with thermocouples - and building thermocoupls

[Roger Heflin]

On Tue, 20 Jun 2000, Rich M wrote:

> Nice one Orin!
> Yes I agree! anyone following this thread should take a look. www.analog.com
> .
> Wish I'd known they were available at that sort of price... I've used the
> 'big brother' AD594 which is fine but expensive, albeit a better accuracy.
> But as most people here probably want this for exhaust gas measurement, a
> few degrees here or there is no sweat! The datasheet also has a good
> temerature/thermocouple voltage reference chart. The AD594 datasheet is also
> worth a read for thermocouple theory and background info.
> Practical note - you still need to terminate the thermocouple wires close to
> the device to avoid temperature differential between the termination and
> cold junction compensator to get maximum accuracy.
> 
> Rich.
> 

Good info I will need to look at it.

On terminating thermocouples:
Where the plug is put, the thermocouple is terminated?  And at this
point you can run normal wire to the computer setup?

I am still trying to understand exactly how these devices work and
exactly what I need.

I have decided to use a 80C52-basic processor.  It has external
address lines and can be programmed in basic or assembler and has
built in a serial interface to get into the chip.   It should be fast
enough for what I need and I will be playing some addressing tricks to
allow me to have quite a bit more ram than the 64k it can address
without tricks.

			Roger

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