On Tue, 06 Sep 2005 20:12:21 +0100, T i m wrote:

The current isn't real.

Doh!

Hmmmm. Yes and no. There is movement of electrons from one metal in a
differentially heated thermocouple to the other, so Yes there is a
current. I expect this varies with the imposed resistive load and tops out
somewhere, so meter readings may vary depending on their resistance.

Believe it or not my physics teacher had a gas-powered radio. It was
Russian-made (or at least the notation was in cyrillic) and had a bank of
thermocouples over a gas flame and a heat sink at the back to keep the
junctions at different temperatures. The radio used thermionic components,
naturally, and the case looked rather like the radio had been involved in
a shoot-out at Stalingrad. It was certainly a good way of impressing a
class of teenagers. The next week a gas-powered refrigerator was our
object lesson in thermodynamics.

http://www.kkn.net/archives/html/QRP.../msg01213.html

gives a useful detour possibility if you are in the midlands.

John Schmitt

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