The units used to provide power to thermostats are
called 'thermopiles' and are a number of thermocouples
in series to get a nominal 0.5V operating voltage.

http://hearth.com/what/gas/howgasworks.html

Of course you can't use a thermopile inside the
oven since both ends would be heated.

Robert

Bill & Pookie wrote:
> 
> Not to argue the point, but here I go, arguing the point.
> 
> All I know about voltage and amps is the EGBDF thingie.  But the
> thermocouple sure appears to be the only source of electrical power in the
> system and it will turn on the main gas jets if the pilot light has heated
> it up enuff.  In fact I have used a battery on the old heater at the
> thermostat to start the thing heating.  "A penny for your fuse box."
> 
> Never measured on so don't know the facts.  Just going by I have seen work.
> 
> Bill
> 
> ----- Original Message -----
> From: "Peter L. Peres" <plp@actcom.co.il>
> To: "Microcontroller discussion list - Public." <piclist@mit.edu>
> Sent: Wednesday, October 20, 2004 7:27 AM
> Subject: Re: [EE]: Temperature sensor for my oven?
> 
> >
> > On Tue, 19 Oct 2004, Bill & Pookie wrote:
> >
> > > In my old system, the thermocouple provides power if the pilot light is
> > > burning.  This is the power that the thermostat supplies to the main
> burners
> > > when the thermostat's points close.
> > >
> > > Just thinking that this power could be measured.
> >
> > Yes but typically a thermocouple at 1000C will produce 20mV. To get any
> > kind of current from that you need a really low resistance circuit and
> > magnet coils with high sensitivity. Those 20mV in a 20mohm circuit will
> > give an amp. You can do a number of things with 1 amp but the circuit
> > needs to be *very* well built. 20mohm is a very low circuit resistance
> > (including the thermocouple wires!!!)
> >
> > Peter
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