Lighting a LED with a candle flame

Lighting a LED with a candle flame

After reflecting on the circuit 'oscillator running on home made thermocouple', and failing to get a LED lighting up yesterday, it all fell into places, and I realized that the means to obtain the required 2V DC for the LED WAS ALREADY THERE.

For the curious and experimenters, here is the complete diagram:

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Please, this is a BIG file, >3 MB

And this is what the very simple circuit looks like:

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Scope is on source, to avoid loading.

This home made thermocouple is really not suited for temperatures above 200 C, not only will the solder melt, but in the top of the candle flame it will simple burn up (> 1000 C there). In the bottom of the candle flame you will be OK for a short while, better is to get perhaps a type E thermocouple, more voltage an it better stands high temperatures.

The LED is not very bright, and it is bright daylight here, perhaps tonight I will try to make a youtube video or better pictures with the LED visible.

The secret to get the LED on, is in fact very simple. The waveform at the gates of the JFETs is limited by the gate source diode junction conducting (max about 1.4 Vpp). So in fact there is already some gate current. Re-directing the gate current through the LED, and decoupling the LED, and moving it so it is ground connected, is all that is required. The voltage over the LED slowly rises as the gate current charges the 100 nF capacitor, and at about 2 V all current goes into the LED, and it lights up.

Reply to
Jan Panteltje
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thermocouple',

ALREADY THERE.

simple burn up (> 1000 C there).

stands high temperatures.

will try to make a youtube video

junction conducting (max about 1.4 Vpp).

capacitor,

How about lighting a candle flame using an LED?

Sylvia.

Reply to
Sylvia Else

On a sunny day (Mon, 01 Oct 2012 23:12:16 +1000) it happened Sylvia Else wrote in :

thermocouple',

ALREADY THERE.

C,

simple burn up (> 1000 C there).

stands high temperatures.

will try to make a youtube video

junction conducting (max about 1.4 Vpp).

capacitor,

Should be possible with 100W LEDs and a some optics. You thought of it, so you build it! We are waiting for your demo.

Reply to
Jan Panteltje

thermocouple',

ALREADY THERE.

formatting link

C,

simple burn up (> 1000 C there).

stands high temperatures.

I will try to make a youtube video

junction conducting (max about 1.4 Vpp).

capacitor,

Try a laser diode:-

formatting link

Reply to
Spehro Pefhany

ocouple',

WAS ALREADY THERE.

36...

e 200 C,

ill simple burn up (> 1000 C there).

ter stands high temperatures.

night I will try to make a youtube video

iode junction conducting (max about 1.4 Vpp).

100 nF capacitor,

Hmm, I'm thinking that with enough power I might be able to get a single LED to light a candle. Of course for the next candle I'll need a new LED. (All the magic smoke will be gone from the first one. :^)

George H.

Reply to
George Herold

thermocouple',

ALREADY THERE.

C,

simple burn up (> 1000 C there).

stands high temperatures.

I will try to make a youtube video

junction conducting (max about 1.4 Vpp).

nF capacitor,

Sure thing. Wrap the leads around the wick and connect to a car battery. ;)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
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Reply to
Phil Hobbs

On a sunny day (Mon, 01 Oct 2012 09:34:49 -0400) it happened Spehro Pefhany wrote in :

thermocouple',

ALREADY THERE.

formatting link

C,

simple burn up (> 1000 C there).

stands high temperatures.

I will try to make a youtube video

junction conducting (max about 1.4 Vpp).

nF capacitor,

Ha!

formatting link

Reply to
Jan Panteltje

thermocouple',

ALREADY THERE.

C,

simple burn up (> 1000 C there).

stands high temperatures.

will try to make a youtube video

junction conducting (max about 1.4 Vpp).

capacitor,

How about extracting light directly from a candle? That is theoretically possible.

More practical would be to get usable LED lighting from ambient RF.

Reply to
John Larkin

ocouple',

WAS ALREADY THERE.

36...

e 200 C,

ill simple burn up (> 1000 C there).

ter stands high temperatures.

night I will try to make a youtube video

iode junction conducting (max about 1.4 Vpp).

100 nF capacitor,

I remember working in a place about 2 miles from a 50KW AM radio station antenna. We could light a little (65 volt) neon indicator NE-51 from a short wire antenna using a series tuned LC circuit with the neon bulb across the inductor or capacitor. I think there is a crystal radio design that uses the same idea to produce a DC voltage from a strong station to power an RF amplifier tuned to a weaker station. No batteries required.

-Bill

Reply to
Bill Bowden

thermocouple',

ALREADY THERE.

200 C,

simple burn up (> 1000 C there).

stands high temperatures.

tonight I will try to make a youtube video

junction conducting (max about 1.4 Vpp).

nF capacitor,

Yeah, I've heard of that last one. The ideal power harvester would use the entire RF band, somehow.

I read, somewhere, that it's illegal (theft) to deliberately steal power from a radio station, or from a power line.

--
John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    
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Reply to
John Larkin

thermocouple',

ALREADY THERE.

200 C,

simple burn up (> 1000 C there).

stands high temperatures.

tonight I will try to make a youtube video

junction conducting (max about 1.4 Vpp).

nF capacitor,

It can't be illegal to "steal" power from a radio station since they are tossing the power away. You are simply picking the power out of their trash bin.

The power line is different. To get power from their lines you would inductively couple and draw power that they aren't otherwise losing. That could be considered theft, even if you aren't terribly close to the power line.

The difference in the two is whether your power usage costs the company anything. In the case of radio, they have no loss. The power company can show a loss.

Rick

Reply to
rickman

thermocouple',

WAS ALREADY THERE.

formatting link

200 C,

simple burn up (> 1000 C there).

stands high temperatures.

tonight I will try to make a youtube video

diode junction conducting (max about 1.4 Vpp).

nF capacitor,

I think there was a case where someone put up an antenna near an AM station, specifically to extract power. That of course reduced the signal strength outboard of the parasitic antenna, which was determined to be theft.

The radio station loses customers and advertising revenue.

--
John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    
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Reply to
John Larkin

thermocouple',

ALREADY THERE.

200 C,

simple burn up (> 1000 C there).

stands high temperatures.

tonight I will try to make a youtube video

junction conducting (max about 1.4 Vpp).

nF capacitor,

About 40 years ago one of the profs built a "crystal" radio using the power from a long-wire antenna (between the EE building and the next (TAM), using an LED as the detector. It received five or six local stations and was playing in the lab 24/7 for at least a couple of decades after I graduated.

Reply to
krw

For a few milliwatts? Have you ever performed field intensity tests at an AM radio transmitter site?

Reply to
Michael A. Terrell

Close to a 50KW AM station, it shouldn't be hard to extract hundreds of watts.

--
John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
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Reply to
John Larkin

In AM times they used to steal energy araond the transmitting tower. The problem was not that little amount of wattage they could catch from the air, but when they started to span long and longer wires across their gardens in the adjacent neighbourhood the transmission field characteristics of the radio station began to change and the radiation pattern was distorted. Only for that reason the "energy theft" had to be prosecuted.

w.

Reply to
Helmut Wabnig

Right. Thanks.

--
John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
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Reply to
John Larkin

Ha! What a profound statement!

Reply to
The Keeper of the Key to The Locks

But then again, you probably copied it from somewhere.

Reply to
The Keeper of the Key to The Locks

This is correct. Above sentence (sorry for the missing h) applied to the country of Kakanien, the Austrian K&K monarchy. K&K stands for Königliche & Kaiserliche Österreich-Ungarische Monarchie.

Even the Kaiser, the Emperor himself on one occasion asked: "Ja dürfen's denn das?" (Are they allowed to do that?)

"Everything which is not assertively allowed, is forbidden!"

w.

Reply to
Helmut Wabnig

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