"Richard Casady" wrote in message
...
On Thu, 9 Oct 2008 19:27:43 -0700, "Calif Bill"
wrote:

Wiki is mistaken. The cold junction is where the temperature can be
measured. But thermocouples are disimilar metals the cause a current to
be
generated between the two metals when heat is applied. Milliamps of
current, or a real small amount. You can make your own thermocouple by
connecting the special thermocouple wire together and heat the junction.
Enough current is caused to be able to pull a solenoid if required. Very
low current solenoid, but still current generated. Check out Omega Corp.
We used to buy the thermocouple wire they manufactured.

The solenoid is a junction, of course. You have dissimilar wires
connected together at both ends. I have one intended to cover the
range -320F to 1800F so which end is hot or cold depends. So what?

Casady

The only reason you need a junction at the other end is so you can have
current flow. The current is caused by the physics of the selected
dissimilar metals in contact in a heated enviroment.