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From: (Doug White)
Newsgroups: rec.crafts.metalworking
Subject: Re: Flame Speaker?
Date: Sat, 06 Jun 1998 02:15:01 GMT

In article <6l98bg$8tv$>, wrote:
>Hello, All!
>Sorry; this is a little off-topic for this group. But I can't think of
>anywhere else that'd be more appropriate, and the SNR of this group is so
>high, and _somebody_ here knows _something_ about _everything_, so here goes.
>I was reading the new Lindsay catalog last night, and was put in mind of a
>persistent rumour from my college lab days. Seems everyone had "heard it was
>possible" to make an open flame - say, from a Bunsen burner - to act as a
>speaker. Nobody had heard or seen it done, but we all knew it was a cool trick
>that we had to track down someday.
>Has anyone ever heard of a method of putting electrodes in or near a flame and
>modulating them in such a fashion that intelligible noise was a result? It'd
>sure be a cool trick if it worked.
>Thanks in advance, and here's hoping for yet another interesting thread!

Been there, done that, won lots of science fair prizes with it.

This was back in the late-60's, and I used a propane torch with copper
wire electrodes coated with salt.  I had a 500 V DC power supply
modulated with an audio transformer.  When properly tweaked up, it
sounded like a 3" transistor radio speaker with a rip in it.

There are other fun things you can do with the plasma stream in a flame,
including making a triode with gain.  You can also propel yourself across
the basement if you are young & forget to turn off the high voltage
before adjusting the electrodes.  Ah, to be young again...

(frankly, it's a miracle I survived my youth at all)

Doug White

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