It's easy enough to do, but the source of calibration will be a problem.

To answer your question...it mainly depends on what degree of accuracy you=
=20
need.

There is nothing mysterious about the device, a simple resistor will vary=20
in resistance and can also be used.

You will need to be aware of the heating effects of the current you force=20
through the diode also. A low power diode in a glass or epoxy package might=
=20
not give the expected results. You might need to go with a power diode=20
which has improved thermal conductivity with the outside world.

Seriously, I'd use a thermocouple if your goal is low cost and you need=20
decent accuracy.

Later.

Art


At 03:01 PM 3/12/04, you wrote:
>-List,
>Anyone here ever measure very low temperatures (-100=BAC) by measuring=20
>Vforward for a given Iforward?
>There are several high dollar diodes out there (GaAlAs, GaAs, and Si) that=
=20
>are extremely well characterized and thus good for the task, but I'm=20
>trying to stay on the cheap here.
>
>Does anyone have any data about Vforward vs Temp for a common (i.e. cheap)=
=20
>Si diode at very low temperatures?
>
>I've been googling for a day and a half now on this project with limited=20
>success.
>Thanks in advance.
>Robert Mash
>740.592.2655
>
>
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