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Can we get to some ballpark numbers to see if it's significant?

Comments:

I'm not tracking with your assertion on the other thread that the effect goes away as the amplitude goes up. Shouldn't this result in a greater assymmetrical heating effect during each half cycle, and therefore increased non-linearity?

OK, back to the calcs (check these and tell me if I screwed up):

120dB below 30mV is 3x10-8V, so we're looking for a number in that ballpark.

In JC's test, the heat current peaks at (diff in Peltier coeffs) x 50uA, right? I can't find the Peltier coeffs, but they are related to the Seebeck coef by Seebeck = Peltier/T, so at 300K the Peltier coeffs should range from 3x10-3 to 3 x 10-4. If you assume worst case diff is 3x10-3, then the heat current is
1.5x10-7 Watts. Probably much lower....

If the junction is 1mm square, the area is 10-6m2.

So, we have:

1.5x10-7 Watts = 400W/mK x 10-6m2 x (temp gradient)
(using 400 W/mK for the approximate thermal conducivity of CU and Ag at 300K)

So, temp gradient is 1.5/4 x 10-3 = 3.75 x 10-4 K/m.

I'm stopping here for now...

If you estimated the thicknees of the boundary over which this gradient occurs, that would give you a temp diff, which you can use to calc the Seebeck effect.

I still think we will come in way below JC's numbers, but I'm not ruling it out just yet...

Peter


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