Re: My ARSG had a melt-down

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Malcolm Watts by way of Terry Fritz <teslalist-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

On 13 May 2003, at 13:34, Tesla list wrote:

 > Original poster: "Daniel Hess by way of Terry Fritz 
<teslalist-at-qwest-dot-net>" <dhess1-at-us.ibm-dot-com>
 >
 >
 >
 >
 >
 > I was running with my original ARSG last night. A 12" diameter disk with 12
 > flying brass electrodes, driven by a 1/20th HP Robbins induction motor. I'm
 > surprised the little motor had the mojo to spin up to speed but it could.
 > This thing was built in the early nineties back when I didn't know what I
 > was doing. No Tesla list, only Lindsey's reprints from the twenties. Since
 > I planted my new RF ground recently, I've been fine tuning this coil,
 > trying to shoot for the magic K values. As it was night, the only light in
 > my shop was coming from the coil itself and the gap.
 >
 > The output was really going great; I'd started with thin purple sparks and
 > as the tuning progressed I was achieving fatter, white sparks when
 > suddenly, the output became sporadic and the tone from the gap became
 > inconsistent. The blue/white light from the gap revealed smoke billowing
 > from the gap itself. Shut down, shop lights on; I'd used a plank of 1/4"
 > hard PVC to mount the fixed electrodes. These electrodes were mounted with
 > 1.25" fender washers (to help dissipate heat, haha!) and these had gotten
 > so hot they pulled through the PVC. More like they boiled their way out.
 > Funny thing is, I had lots of run time on this gap before but was using it
 > with my old glass & foil cap. This time I was using a MMC. I hated that it
 > was destroyed but then again, the way it went out was so cool. I could
 > replace the PVC panels with either phenolic or G10 but the entire rotor was
 > also made from 1/2" PVC. So maybe I will conclude that this incident was a
 > friendly warning from God not to use PVC for construction of a RSG and just
 > retire the whole thing.
 >
 > One interesting side note; I never noticed this before but as I'd raise or
 > lower the rotor speed, I could hear a combination or beat tone (where two
 > different frequencies partially coincide creating a perceived third tone
 > caused by the incidence of the two frequencies adding positively and/or
 > negatively). I would slowly change the rotor speed, attempting to
 > synchronize the two pitches. When this happened, (synchronize the two
 > frequencies and the beat tone goes away) even though it would only last a
 > few seconds, the coils output would increase dramatically, then decrease as
 > the two frequencies moved apart. Even the fluorescent tubes (which were
 > turned off but would still glow in the field of the coil) would get
 > brighter in step with the coil's output. Conversely, when the two
 > frequencies were at their maximum difference, the coil and the fluorescent
 > tubes were at their lowest output.
 >
 > This effect was the most noticeable at the lower rotor speeds, in the
 > neighborhood of 60 - 80 bps. I know that one of the two frequencies I heard
 > was the sound of the RSG electrodes presenting and thus, firing, but am
 > unclear what the other sound was. Perhaps the output sparks from the toroid
 > itself?
 >
 > Comments welcome,
 >
 > Daniel

Sounds like a classic case of the breakrate being a multiple of or
beating with the mains frequency.

Malcolm