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Re: Single 833A VTTC

Original poster: "Teslacoil Workshop" <workshop@xxxxxxxxxxxxx>


My guess is that Cameron's observation can (should?) be replicated by
changing the number of turns on the feedback coil and/or adjusting the
resistance on the RC grid circuit.

Something about raising the feedback coil into the HV region of the
secondary coil bugs me for some reason (but so does solid state *smirk*).

That said, there is no doubt that Cameron's coil works quite well as

I used a 555 ic (and later a guitar amp... but that's another story) to
drive/modulate a VTTC and it worked quite well. That was 8 years ago so I'll
have to dig for schematics if I still have 'em. It's easy enough to figure
out. As John Freau (sp?) discovered; it's all in the grid!

Jeff Parisse

----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Saturday, August 12, 2006 5:08 AM
Subject: Re: Single 833A VTTC

> Original poster: "Steve Ward" <steve.ward@xxxxxxxxx>
> Hi Cameron,
> Very interesting (and impressive!) results.  It seems like you just
> found a sweet zone for the coil.  I might have to think on this
> feedback coil positioning issue... interesting indeed.  I dont think i
> ever positioned my feedback coil so high, maybe only 3" at most.  The
> usual issue was arcing from the secondary to the winding.  I never had
> the chance to scope out a VTTC to really study its operation in detail
> (particularly the feedback part).  I still have a pair o 833C's
> waiting for a use ;-).  So many ideas, so little time...
> I had plans to make a solid state and vacuum tube integrated system.
> The tank circuit would look like your typical VTTC, but the grid drive
> would be solid state.  The idea was that it could give more control
> (and perhaps some insight) over the feedback loop.  Pulse width, bias
> and drive voltage, and phase relationship could all be finely
> controlled to produce best results.  I also intended to build a multi
> kW plate supply using transistors and ferrite transformers (like
> newere microwave ovens use).  But this would be roughly equivelant to
> a plain transformer power supply.  It would probably not be reproduced
> by many (if any) other coilers.