Shouldn't the higher current produce the higher voltage drop??
As the forward voltage drop is ~exponential with current, I think you may
need a 10:1 ratio for the 2 currents to get a reliable estimate.

One suggestion I was going to make re the temp sensor is to connect a
couple of transistors in darlington configuration and then the "base" to
"collector". This produces a quite flat voltage/current charecteristic, a
voltage drop of about 1.2V and twice the temperature coeficient of a single
diode.


Richard P





I have been experimenting with sending 2 currents through a diode but find
no real change in the voltage drop difference as temp changes.

@67F  1mA = .675volts  2mA = .589volts =  .089volts diff.
@77F  1mA = .611volts  2mA = .521volts =  .090volts diff.






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