> ------------------------------
>
> Date:    Mon, 18 Aug 2008 06:19:02 EDT
> From:    Frank Condelli <RAlanen@AOL.COM>
> Subject: Re: Dometic Fridge propane operation stuff
>
>
>         ...First time I ever hear of a Thermocouple that generates electricity !
>
They all do Frank, that's how they work!  Same thing that causes
galvanic corrosion, you have two different metals fused at the
measurement junction, and if that junction is at a higher, or lower,
temperature than the other ends of the wires, you generate a voltage (in
the millivolt range).  Biggest problem with TC's is that the voltage
generated is proportional to the temperature *differential* between the
measurement junction (TC tip) and the Meter (cold junction), so you
still need to be able to measure what the cold junction temp is to get
an actual temperature.  In the fridge use, however, this is not a
problem, since all you want to know is whether the heat chamber is
significantly higher in temp than the cold junction, not what the actual
temp is.  TC's great for that since you can use the millivolt signal to
trip your circuit, or use in a comparator.  Cheers,

Keith Hughes
'86 Westy Tiico (Marvin)