[sci.electronics] Sound Amplification by Combustion

bobby@hot.caltech.edu (Bobby Bodenheimer) (08/19/89)

 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.
 
 I'm interested in this so if someone could please provide
 background on the discussion, summarize it, or just give
 me some references, I'd greatly appreciate it. Also, is
 this newsgroup archived anywhere?

 Thanks much,
    Bobby Bodenheimer				@hot.caltech.edu
// BITNET: bobby@caltech.bitnet                 |
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morris@jade.jpl.nasa.gov (Mike Morris) (08/20/89)

(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.
> 
> I'm interested in this so if someone could please provide
> background on the discussion, summarize it, or just give
> me some references, I'd greatly appreciate it. Also, is
> this newsgroup archived anywhere?
>
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.

Mike Morris
UUCP: Morris@Jade.JPL.NASA.gov
#Include quote.cute.standard   | The opinions above probably do not even come
cat flames.all > /dev/null     | close to those of my employer(s), if any.

larry@kitty.UUCP (Larry Lippman) (08/21/89)

In article <1625@jato.Jpl.Nasa.Gov>, morris@jade.jpl.nasa.gov (Mike Morris) writes:
> 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 built one myself during the mid-60's when in college, and I recall
getting the idea from an article in Popular Electronics.

	I used an old David Bogen 100 watt PA amplifier, an AM modulation
transformer, and a variable high voltage power supply (1 kV max).  A glass
rod was used to "seed" the flame with sodium ions and render it more
conductive.  I used two insulated carbon rods as electrodes (one cannot
use the burner itself as one electrode since the flame is "insulated"
from the burner).

	It really worked and reproduced sound.  I found that the best
reproduction occured with higher velocity flames.  I first used a laboratory
blast burnder for glassblowing which used compressed air and natural gas
(okay, so I built it in a university research lab on their time :-) ).
It also worked with an acetylene-air Prestolite torch.  The best results
were obtained with the hot, high velocity flame of an oxyacetylene welding
torch.

	It was an interesting project which exhibited good high frequency
response, but not too practicable for use in the living room. :-)

<>  Larry Lippman @ Recognition Research Corp. - Uniquex Corp. - Viatran Corp.
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ems@Apple.COM (Mike Smith) (08/22/89)

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

This is the obligatory disclaimer of everything. (Including but
not limited to: typos, spelling, diction, logic, and nuclear war)

gordon@prls.UUCP (Gordon Vickers) (08/23/89)

        I remember that article too.
        I was in high school at the time and we tried it in our electronics
   class.  Our flame was barely adequate, four to six inch high (I think a
   minimum of six inches was recommended). The sound was pretty distorted
   but we didn't concern ourselves with impendance and flame size was too
   small. We just used a common propane torch.
        As I recall, the article mentioned (or suggested) connecting
   ones HiFi to a central heating furnace. Maybe a nice idea unless you want
   sterio :-)
        Hmmm, if NASA hears of this, I wonder if they'll start playing
   the National Anthem during shuttle launches ?        :-)

michael@xanadu.COM (Michael McClary) (09/18/89)

In article <3344@kitty.uucp> larry@kitty.UUCP (Larry Lippman) writes:
>
>	I used an old David Bogen 100 watt PA amplifier, an AM modulation
>transformer, and a variable high voltage power supply (1 kV max).  A glass
>rod was used to "seed" the flame with sodium ions and render it more
>conductive.  I used two insulated carbon rods as electrodes (one cannot
>use the burner itself as one electrode since the flame is "insulated"
>from the burner).
>
>	It really worked and reproduced sound.  I found that the best
>reproduction occured with higher velocity flames.  I first used a laboratory
>blast burnder for glassblowing which used compressed air and natural gas
>(okay, so I built it in a university research lab on their time :-) ).
>It also worked with an acetylene-air Prestolite torch.  The best results
>were obtained with the hot, high velocity flame of an oxyacetylene welding
>torch.

Want it really loud?  Add a permanent magnet with the field at right
angles to the gap between the electrodes.  This makes an MHD motor
that accellerates the gas at right angles to the current and the
magnetic field.  Flat response from DC to low radio frequencies if
you do it right.  (Too much combustion product to use to pressurize
your house, though.  B-) )

rob@wiley.UUCP (Robert Heiss) (09/27/89)

In article <g65Bd#=michael@xanadu.COM> michael@xanadu.UUCP (Michael McClary) writes:
>Want it really loud?  Add a permanent magnet with the field at right
>angles to the gap between the electrodes.  This makes an MHD motor
>that accellerates the gas at right angles to the current and the
>magnetic field.  Flat response from DC to low radio frequencies if
>you do it right.  (Too much combustion product to use to pressurize
>your house, though.  B-) )

Did the setup without the permanent magnet depend on the earth's magnetic
field in order to make sound?

	Robert Heiss    uunet!wiley!rob