A number of years ago, I read about a hiker who built a portable thermopile generator. He used a metal smokestack pipe as a flue he would place over a campfire. The smoke stack looked like a porcupine as bimetallic elements were sticking out from it perpendicular to the surface. Supposedly it generated enough current for him to run radios and the like.
I've lost the reference to it. Does anyone have any idea where I might find it? Googling had been useless as all it brings up are Honeywell
I went down to my local HVAC parts store and bought one of those Honeywell thermopiles (they are supposed to detect the pilot light and generate enough juice to hold the relay open that supplies the pilot. If it blows out, the gas shuts off). They are about $35 ea. I couldn't get 700mv out of it... tried the hot air gun, fire... I was hoping several of em in series might be able to fire up a wide input dc to dc switcher. Results so far are inconclusive...
I just happened to measure that this morning. Not much voltage at all at only a few degrees difference, but as long as the thing does not melt, it should work up into a couple hunderd degrees.
I've heard of people using thermoelectric coolers between their Coleman stove and cooking pot, to generate electricity at camp. You'd want to use the ones that can stand thermal cycling, of course--try Ferrotec. The cheaper ones are made with soft solder, and won't stand much cycling--like 100 cycles MTBF.
Of course, you could use a small steam engine running a bicycle generator.....
In Pierre Lorain's excellent book "Secret Warfare" he describes one made by SOE for resistance use during WW2. It had 350 thermocouples (Cn-Cr) in a brazier. With a small fire it could charge a 6 volt battery at 1 Amp. I have seen a photo of one, but can't recall where now. It looked to be about 5-6" diameter and maybe 10-12" high.
Seeback(?) effect is really inefficient. I don't know what exotic compounds and intermetallics can do, but I recall the best not-too-exotic combination is silicon and germanium.
As I recall, such was used in Voyager 1 and 2 or so, combined with a ball of plutonium, to produce 100 watts or so.
Tim
--
Deep Fryer: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
IIRC, I've seen electric fans that sit in a stovepipe and derive their power from tapping the temperature gradient from the air to the outside of the pipe.
Best regards, Spehro Pefhany
--
"it\'s the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Thermopiles aren't forgotten. Your search techniques needs improvement - if Honeywell comes up too often put a minus sign in front of it when you search. Or use google advanced search and put it in the block marked: "without the words"
Use Scroogle and put a -com and you get the edu, org, gov, etc., sites
I remember reading a Scientific American, Amatuer Scientist article on the subject. It is basically a large number of thermocouples wired in series. They showed a design where two wooden doughnuts have the iron/copper thermocouples between them with all of one set of junctions on the inside of the circle (the hot side) and the opposite side on the outside with a bunsen burner heating the hot side. Wires were about 8" long . . . iron,copper,iron,copper, etc..
The Rusians used a large number of thermopiles heated with decaying radioactive isotopes to heat the hot side. They were used in their space program and in remote areas to send telemetery data back to base.
See
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read to the end where it mentions thermopiles
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There was scarcely a shortage of brave Frenchman during the war, nor of brave Englishman (and women of course). Anyone caught by the Germans with one of those large thermopiles was a goner.
Nor, ironically, of brave Germans who opposed the Nazis. In fact there was more opposition in Germany than in France, impressions to the contrary notwithstanding.
Actually all across Europe. I do recall seeing in a memorial somewhere, to the Resistance, the numbers in various countries. France was pretty well down the list, which was a bit of a shock to me, as I grew up hearing and reading all about the "French" resistance. I understand that the French numbers grew a lot when it was apparent an invasion of France was coming.
But anyway Win is correct. Torture and death awaited anybody caught with any part of a radio, generator, weapon, etc. And indeed even being out on the street when the Nazis took reprisals.
The crying shame is that many of the offenders walked away without penalty.
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