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Old 14th Apr 2010, 9:28 pm   #1
malvision
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Default Gas powered wireless/radio set

This might seem a silly question but i remember reading a article in pratical wireless/television in the 80s.That there was such a thing as a gas powered wireless

Was i dreaming or is there such a thing

Thanks
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Old 14th Apr 2010, 9:52 pm   #2
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Default Re: Gas powered wirless/radio set

Wasn't in an April edition by any chance?
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Old 14th Apr 2010, 9:52 pm   #3
Phil G4SPZ
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Default Re: Gas powered wireless/radio set

I've also been told as a schoolboy - by a teacher, so I believed it - that a gas set was marketed, but I think the question has cropped up and been discussed here before. I read that someone had worked out that although it would be technically possible, but totally impractical, to generate a few mA of HT from a gas-heated thermopile, it would be impossible to generate enough current to run the valve heaters. I think the conclusion was that it's an urban myth, but I may be wrong.
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Old 14th Apr 2010, 9:59 pm   #4
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Default Re: Gas powered wirless/radio set

This thread may be helpful:

https://www.vintage-radio.net/forum/...+powered+radio
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Old 14th Apr 2010, 10:10 pm   #5
David G4EBT
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Default Re: Gas powered wirless/radio set

Quote:
Originally Posted by malvision View Post
Was I dreaming or is there such a thing
Yes there was, but AFIK, only as a novelty.

I spent my career in the gas industry, mostly on the technical side, and we sometimes gave demonstrations to schools, one aspect of which was to power a transistor radio from gas-heated thermocouples.

Until recent times, the flame failure device on gas central heating boilers was a thermocouple. (They're still used extensively on gas hobs and fires). Modern boilers are more sophisticated as, energy saving requirements forbid the use of permanent pilots on central heating boilers produced nowadays.

The proper function of the thermocouple when the pilot flame plays upon it is to generate a small amount of current at low voltage, sufficient to energise a solenoid in a gas valve, which then keeps the valve open to allow gas to pass to the main burner when the boiler thermostat/cylinder thermostat/room thermostat and clock call for heat.

The solenoid valve is spring loaded and if the pilot light fails, the current to the solenoid stops so it is de-energised and slams shut to cut off the supply of gas to the boiler. Only by re-lighting the pilot and pressing open the solenoid valve manually until the thermocouple generates sufficient current to hold the valve open on its own accord, can the gas valve stay open again.

If several thermocouples are connected in series and a gas flame played upon them, they will generate enough voltage at sufficient current to power a transistor radio., but it would take a very large bank of them to power a valve radio, or a TV.

FWIW, I think that modern boilers without a permanent pilot rely upon the phenomenon of flame rectification. First, thev fan starts up to purge the boiler combustion chamber, then gas is passed to the pilot and ignited by a spark. A minute AC current is passed through the flame, rectified to DC and opens the main DC operated gas valve. No flame = no DC = no gas to main burner.

Sorry to write such a long answer to such a short question - I'm afraid I'm better at verbosity than brevity - but I hope it's of interest.

David.
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Old 14th Apr 2010, 10:52 pm   #6
malvision
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Default Re: Gas powered wirless/radio set

Thank you for your comments and links most intresting
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Old 15th Apr 2010, 8:26 am   #7
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Default Re: Gas powered wirless/radio set

Looks like those kerosene radio lanterns are still in production:

Teg Lantern
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Old 15th Apr 2010, 10:20 pm   #8
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Thanks, PSValves, I'll be ordering one!
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Old 16th Apr 2010, 7:58 am   #9
David G4EBT
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Default Re: Gas powered wireless/radio set

Out of curiosity, I checked the output of a single thermocouple (as used as a flame failure device on gas central heating boilers) to see how much power it would generate.

As can be seen from the pictures, with the tip of the thermocouple glowing red, as they sometimes are in use, it generates just 43mV at 47 uA, so in a thermopile comprising a bank of thermocouples, it takes quite a a lot of them to generate sufficient voltage at sufficient current to power a radio.

Hopelessly inefficient of course.

I can't remember how many thermocouples we used to power a transistor radio in demonstrations to schoolchildren, but rather more than I'd imagined. I don't know if thermocouple junctions made of different combinations of dissimilar metals would generate more voltage at greater current. I doubt it, given that the thermocouple I used has to energise a solenoid to hold open a spring loaded gas valve which will slam shut the instant the flame ceases, and must do this year in, year out, 24/7 for many years. (The one I used was a spare for my 20-yr old boiler which I've just replaced, in which the original thermocouple had never failed).

David.

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Old 16th Apr 2010, 9:17 pm   #10
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Default Re: Gas powered wireless/radio set

Very interesting findings, David; 43mV when open-circuit, and 47uA when short-circuited. That suggests a requirement for 200 or more parallel strings, each of over 2,300 thermocouples in series, to generate 100 volts HT at 10mA for a radio! I can't believe that. There must be different types of thermocouple used in the gas-heated generator that are more efficient.

However, it certainly proves how sensitive the solenoid in a gas valve must be, holding open on less than 2 microwatts of power from the thermocouple. Knowing how strong the spring is, I suspect the solenoid doesn't hold the valve open directly, it probably holds a latch against a very much lighter spring. Apologies, mods, as I know this thread isn't about gas valves!
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Old 16th Apr 2010, 10:08 pm   #11
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Default Re: Gas powered wireless/radio set

uhm, why do you all asume 100V?
I have a old noname radio here that run 22,5V B+ and 1.5V for filaments (3 tubes), true no roomfilling sound but enough to listen in a quiet room not to mention if I connect phones.
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Old 16th Apr 2010, 10:59 pm   #12
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Default Re: Gas powered wireless/radio set

Quote:
Originally Posted by David G4EBT View Post
As can be seen from the pictures, with the tip of the thermocouple glowing red, as they sometimes are in use, it generates just 43mV at 47 uA
I can believe 43mV, but not 47uA. I am sure the short-circuit current of a heated thermocouple is much higher, maybe even an amp.

Bear in mind that a flame-failure solenoid is wound with thick wire, and has fairly chunky terminals so as to keep added resistance to a minimum (important when you only have 43mV driving voltage!). Whereas the photo shows longish test leads, croc clip connection, and a standard DVM trying to measure short-circuit current... with this amount of extra resistance, no wonder the current indicated is small!
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Old 17th Apr 2010, 9:30 am   #13
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Default Re: Gas powered wireless/radio set

This chap has taken one to bits and has some pictures of the thermopile exposed: http://www.energy4free.info/html/the...ectricity.html

Apparently the output is up to 3w which should be plenty to power most portable radios. Certainly, the set built into the base wouldn't need to be anything special.
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Old 17th Apr 2010, 10:20 am   #14
kalee20
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Default Re: Gas powered wireless/radio set

Now that sounds credible... and if the output is 3W, it is enough to operate a valve portable via an inverter!

Maybe I ought to order 2. The price in the link in post #7 is cheaper...
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Old 17th Apr 2010, 11:19 am   #15
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Default Re: Gas powered wireless/radio set

I have heard the one about the gas powered wireless before. Surely that would only have been practical if you had a small engine using the town gas supply instead of petrol.
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Old 17th Apr 2010, 11:34 am   #16
kalee20
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Default Re: Gas powered wireless/radio set

OK That's it, I've ordered 2.

I have a Vidor CN420a portable radio (4 valve superhet), currently running from four Nicads (4.8V), which operate an inverter providing LT and HT. Current drain is 170mA. So at this rate, the two TEG lanterns should generate 6V (at which my inverter will draw 130mA-ish. Watch this space!

Thinking about the boiler flame-failure thermocouple above, while it does run very hot, thermodynamic effectivity probably isn't very good because it's just sitting more or less statically at a high temperature. When optimised, a thermal device needs a hot surface, a cold surface, and an easy flow of heat between them. And the boiler thermocouple's cold junction is a fair distance away and I can't see heat flowing readily from the hot tip to the cold junction (wherever it is), so the power output, while sufficient for the job, won't be earth shattering!

Last edited by kalee20; 17th Apr 2010 at 11:35 am. Reason: It's a Vidor 420a not a 430a
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Old 17th Apr 2010, 12:05 pm   #17
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eagerly watching this space Kalee20
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Old 17th Apr 2010, 12:26 pm   #18
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Default Re: Gas powered wireless/radio set

There is a gas powered radio in Leicester's Gas Museum, on the Aylestone Road.
Well worth a visit, by the way.
Small photo of radio on this page.
http://www.gasmuseum.co.uk/gashome.htm
There was also gas traffic lights in London in 1868. How about the first disco in 1922 ! All on the same page.
Richard.
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Old 17th Apr 2010, 9:59 pm   #19
kalee20
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Quote:
Originally Posted by Neil Purling View Post
I have heard the one about the gas powered wireless before. Surely that would only have been practical if you had a small engine using the town gas supply instead of petrol.
That would work, but it's inelegant (burn gas in a combustion engine, turn the heat into motion, turn the motion into electricity).

The thermoelectric generator removes one step (burn gas, turn the heat into electricity).

These days, it would be even nicer to use the gas directly in a fuel cell and get electricity directly, eliminating the heat-producing step. Unfortunately we're not there yet...
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Old 17th Apr 2010, 10:44 pm   #20
Peter.N.
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Default Re: Gas powered wireless/radio set

I remember this radio from many years ago but I thought the one I saw was in the States. Those Peltier modules they use in coolboxes would I should think produce a useful ammount of power, you can actually buy just the modules now.

Peter
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