Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!brutus.cs.uiuc.edu!apple!ems
From: ems@Apple.COM (Mike Smith)
Newsgroups: sci.electronics
Subject: Re: Sound Amplification by Combustion
Keywords: singing flames
Message-ID: <3738@internal.Apple.COM>
Date: 21 Aug 89 20:16:26 GMT
References: <11652@cit-vax.Caltech.Edu> <1625@jato.Jpl.Nasa.Gov>
Distribution: usa
Organization: Apple Computer Inc, Cupertino, CA
Lines: 43

In article <1625@jato.Jpl.Nasa.Gov> morris@jade.Jpl.Nasa.Gov (Mike Morris) writes:
>(Bobby Bodenheimer) writes:
>>
>> I'm new to this newsgroup, but someone told me there was a    
>> discussion here a few months ago about amplifying sound by
>> combustion or singing flames or something like this.

>In 1969 I was touring Cal Poly Pomona during a science fair, and an exhibit
>there was a "singing flame".  The student told me the original info was from
>a old Popular Electronics or Radio Electronics.
>
>The flame has excellent high frequency response, but a lousy low end.
>It must be "doped" with some kind of a glass rod.
>Sorry, that's all I remember.

I read the original article in Popular Whatever in the late '60s.
What I remember:

Frequency response depended on flame size.  Larger flame, better bass.
Smaller flame, better highs, but poor bass.  The flame needed to have
it's conductivity enhanced by adding ions (small amount of plain table
salt at the bottom electrode) so that the amplifier voltage could be 
kept down.  To drive it required a relatively high voltage output amp
(but not outragiously so) and I think it had a high impedance.

Basic structure is a gas flame with two electrodes in it.  One at the 
top, the other at the bottom.  Each electrod is hooked to one wire
from the amplifier.  A small(!) amount of table salt solution was 
used on a rod at the bottom of the flame to add sodium ions to enhance
conductivity.  The technology was, well, trivial.  No magic.  No special
gimics or magic electrods or mystical dopants.  Any electrod that 
wouldn't melt and most any salt would work.  The bigest problem was
eliminating the 'hiss' from the flame...


-- 

E. Michael Smith  ems@apple.COM

'If you can dream it, you can do it'  Walt Disney

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