Dealing with thermocouples - and building thermocoupls

[Rich M]

> -----Original Message-----
> From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
> Behalf Of Roger Heflin
> Sent: 20 June 2000 15:01
> To: diy_efi at diy-efi.org
> Subject: RE: Dealing with thermocouples - and building thermocoupls
>
> 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?
>

The Analog Devices data sheet for AD594 contains some good reading on the
principles of thermocouple operation and application.
However the thermocouple is terminated, whether plugged into a proper
socket, soldered to a pcb, or screwed into a terminal block, this
termination must be close to the input pins of the IC (which incorporates
the cold junction compensation) to ensure that there is no temperature
differential between the cold junction compensation (ie. the IC) and the
termination which will create an error. This error is directly related to
the temperature differential, ie. 1deg. diff. gives 1deg. error, so we're
probably not talking big numbers. The output signal from the IC can then be
carried a distance to the microcontroller.

Rich

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