Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!usc!apple!xanadu!michael From: michael@xanadu.COM (Michael McClary) Newsgroups: sci.electronics Subject: Re: Sound Amplification by Combustion Keywords: singing flames Message-ID: Date: 17 Sep 89 17:20:11 GMT References: <11652@cit-vax.caltech.edu> <1625@jato.jpl.nasa.gov> <3344@kitty.uucp> Reply-To: michael@xanadu.UUCP (Michael McClary) Organization: Xanadu Operating Company, Palo Alto, CA Lines: 23 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-) )