🚀 go-pugleaf

In article <3086@watdcsu.UUCP> sgcpal@watdcsu.UUCP (P.A.ul Layman [EE-Device Physics]) writes:
>After consulting my undergrad text on the subject I found a picture of
>such a device which was (maybe still) manufactured by 3M.  It produced
>200mW at 9V.  It could run for 24 hrs on a tank of fuel (kerosene) that looks
>like the one on a standard coleman lattern.  It goes on to say that the
>thermocouples(I count 6) were hermentically sealed.  Therefore expensive?

I know of no ordinary thermocouple junctions that put out 1.5 volts with the
temperature differential available as described.  With a 1000 degree F
differential, iron-constantan thermocouples put out about 30 mV. [I know
that thermocouples do not actually respond to temperature differentials, but
rather to temperature gradients.]  Probably what are shown are thermopiles
which are composed of many thermocouples in series.

If you want to build your own, you need to place many, many thermocouples in
series.  Note that the tabulated voltages for thermocouple pairs are actually
open-circuit voltages; if current is drawn from the thermocouple, the hot
end will be cooled and the cool end will be heated.  A good source for the
wire, if you are interested, is:  Omega Engineering, Inc., One Omega Drive,
Box 4047, Stamford, CT 06907.
                                          Barry L. Ornitz