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Registered Member #229
Joined: Tue Feb 21 2006, 07:33PM
Location: Romania
Posts: 506
With a bit of imagination you can find a solution. I remember that years ago i experimented a low voltage spark gap for my ignition coils, inspired by a schema of very early microphones. Shortly, it was a graphite rod, with the ends on two metalic supports. The middle of the rod was connected through a plastic stick to the membrane of an audio difusor, connected at 50 Hz. The membrane vibrations opened-closed the circuit with some sparks (do not imagine something huge), from my coils. A rotary spark gap, made with a collector from electric motors, can be another option. The arc burns easier before graphite electrodes ( i tryed myself for a 2 kV system), but smell awfull.
Registered Member #212
Joined: Sun Feb 19 2006, 05:42PM
Location: Texas
Posts: 20
I made a tiny SGTC as an experiment that used a ~1kV oscilloscope transformer. The gap between the two pieces of wire I used was probably as small as a 40 gauge wire, and the TC didn't work very well either.
However, a rotary spark gap with brushes or something like a car distributor might work nicely for a TC operating at such a "low" high voltage.
Registered Member #87
Joined: Thu Feb 09 2006, 01:36PM
Location: San Jose
Posts: 191
Oil might be going a little far for the tiny coil it already is, but brushes seem interesting. Less energy wasted in a spark. I'd have to have a bit of tension on the brushes against the contacts to keep the oil form preventing contact(misfiring if you will). Would copper suffice for electrodes and brushes?
Registered Member #135
Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735
Copper wire brushes on a copper foiled rotor may be a problem. If a single strand makes full contact before the others it will cause a pinhole burn on the contact rotor.
What you might be able to do is get replacement carbon brushes that already have springs on them, hope that they are flat faced to contact the distributor/rotor, and go that way. The springs on the carbon brushes are generally constant force springs, so as the carbon wears you always get the same contact force, which is also important.
Registered Member #87
Joined: Thu Feb 09 2006, 01:36PM
Location: San Jose
Posts: 191
Well, going against everything that sounds like a good idea, I'm going to try for a static gap. My lash up will be electrode material held apart by a fuse holder. Easily adjustable, and easy to solder as well. I'll eventually build a tiny srsg, but this will do for the moment. That said, would tungsten expand enough to throw off the gap size when heated?
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
Cool, I've always wanted to see if this would work I think Vasil made a spark gap that worked with 4kV from dual MOTs. Low voltage spark gaps that I've seen use large diameter tungsten or platinum faces with a very small gap between them that can be adjusted by a screw.
Vasil, when you say "audio difusor" I guess you mean loudspeaker?
Registered Member #97
Joined: Thu Feb 09 2006, 05:40PM
Location:
Posts: 61
Good luck with your low voltage spark gap, but if it fails what about a low pressure spark gap? The lower pressure would certainly lower the voltage breakdown, but I don't know about quenching. I bet that quenching would be much more difficult at low pressures.
Registered Member #316
Joined: Mon Mar 13 2006, 01:30PM
Location: Marietta, GA
Posts: 212
I once made a spark gap that fired at about 300v from a photoflash board and cap just to see if it would work. It took forever to adjust but it actually did fire reliably. I think if 300v worked, then 1kv will be much easier.
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1kv Spark Gap/Tesla Coil
I think Vasil made a spark gap that worked with 4kV from dual MOTs. Low voltage spark gaps that I've seen use large diameter tungsten or platinum faces with a very small gap between them that can be adjusted by a screw.