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You're killin me...

I'm at home, no data here..

You said Cu at 400w/mk. there's gotta be a length in there somewhere..Cu is 10.2 watts/inch-degree C. (sorry about the units, they say memory is the second thing to go)

Assuming the effect is real...It gets kinda tuff calculating it, because the diffusivity of the materials comes into play..as the gradient formed at audio frequencies is heavily dependent on the speed at which generated heat flows, both away from and towards the junction..so I can't readily calculate the zone or boundaries over which the heat can spread..

I'm not sure I can calculate with any accuracy the total effect, if I include Seebeck, Peltier, Carnot, and Joule..

""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?""peter..

I'm not sure..that's why I asked my initial question..

But, consider the effect conversion efficiency..When the hot to cold difference is greater, the peltier efficiency goes down..So, for higher amplitudes, less conversion occurs. Yes, for Seebeck, it goes up with difference, but for the lengths of material on either side of the junction being discussed, thermal conductivity plays the great dissipator role.

That modulation of Peltier efficiency will happen at audio rates very near the junction (remember I Wag'd about 10 to 100 microinches??).

Those distances are verifiable for silicon, just look at the transient thetaJc stuff in the IR hexfet books...

Hmmmm..consider this...Assume a junction...Then, instantly apply lots of current....

Immediately, the peltier efficiency is some value (nano time frame).

As heat is absorbed(gradient forming), the peltier efficiency starts to go down.

As the structure continues to settle in, the peltier eff. still goes down..

Eventually, the eff. will stabilize at some structurally related number..But, before that happens, it is dominated by diffusivity of the materials. Before it stabilizes, it is horribly non linear..

But the efficiency is actually tracking in some fashion the slew rate of the current...which is the derivative of the voltage.

So, the dissipative loss is a function of the current slew rate, and that is quite non linear..

If we can really calculate the possible peltier/seebeck losses, we have to compare them to the joule losses of the IC..and those are definitely low..30mV/10Kohm/milliohms....

I wonder if the thermoelectric conversion losses are really that low compared to the resistive losses of an IC..in series with the load resistance of 10K..

Cheers, John


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