Re: [TCML] New 833C VTTC - poor performance

["DC Cox" <resonance@xxxxxxxxxxxx>]

The alternistor (Digi-Key Electronics) works well (800 V 25 Amp) as it is
designed to switch inductive loads and is more robust than a standard
triac.  It only costs a few dollars more than a triac but won't blow on you
when you are demo-ing your coil to a group.

Digi-Key p/n Q8025R6 is very robust and will handle the job without
failure.  Approx $7.23 in single lots.  Or, use, as John recommended, a very
robust SCR.

Dr. Resonance





On Sun, Aug 10, 2008 at 9:56 AM, Kris Grillo <kristianisawesome@xxxxxxxxx>wrote:

> Hey list,
>
> I GOT IT!!! I finally found the problem. The grid coil was wired BACKWARDS.
> I switched the leads and got 18" arcs instantly, without any plate glow!
>
> Thanks to everyone who offered help. I have learned a lot with this
> project. Once I recheck all the tuning and tweeking, I'm on to building the
> staccato controller (the eastern voltage research one). Anyone have any
> suggestions for a triac?
>
> Thanks again,
>
> Kris
>
>
> --- On Sat, 8/2/08, futuret@xxxxxxx <futuret@xxxxxxx> wrote:
>
> > From: futuret@xxxxxxx <futuret@xxxxxxx>
> > Subject: Re: [TCML] New 833C VTTC - poor performance
> > To: tesla@xxxxxxxxxx
> > Date: Saturday, August 2, 2008, 1:07 PM
> > Kris,
> >
> > You have to retune the primary as you increase the power
> > and as the sparks get longer.? A primary tune point
> > that's best
> > for a 10" spark, will be the wrong tune point for a
> > 20" spark.
> > This is because the length of the spark acts as an extra
> > capacitor and changes the resonant frequency of the
> > secondary
> > while the spark is being produced.? You'll need to tune
> > outward
> > on the primary, (use more turns), as the sparks get longer.
> >
> > This is most likely the problem you're having since I
> > can't think
> > of any other good reason for the weak sparks and red tube
> > plate
> > you're seeing.?
> >
> > 20 turns on the grid coil is probably OK.? You can try
> > tapping
> > off at 16 turns or so, but I doubt it will help.
> >
> > Cheers,
> > John
> >
> >
> > -----Original Message-----
> > From: Kris Grillo <kristianisawesome@xxxxxxxxx>
> > To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> > Sent: Fri, 1 Aug 2008 8:03 pm
> > Subject: Re: [TCML] New 833C VTTC - poor performance
> >
> >
> >
> > John, list,
> >
> > "I assume you have a breakout point above the toroid
> > (about 4 to
> > 5" tall or so maybe)"
> >
> > I do have a breakout that extends 4" above the toroid.
> >
> > "You have to tune at full power. If you tune at low
> > power, the tune point will
> > be wrong at high power."
> >
> > I'm not sure what you mean by full power. I brought the
> > variac up slowly until I
> > noticed the plate glow, then I backed down a tad and made
> > adjustments. I
> > repeated this process for hours. Once I got the primary
> > dialed in, I didn't mess
> > with it at all. The power input couldn't change the
> > frequency, could it?
> >
> > "I assume your caps can handle the power? Are they
> > getting hot?"
> >
> > As far as I know, they can handle the power. They are the
> > TDK UHV-9A 202K 40KV.
> > One for the tank and one for the grid leak. They were on
> > again off again for
> > quite a while and they do not even get warm as far as I
> > could tell from
> > occasional touch testing.
> >
> > "Also if you have an 833A, you can try that."
> >
> > I don't have one.
> >
> > "You can try using a higher grid resistance too. Just
> > put another resistor in
> > series with the one you have."
> >
> > I don't have an appropriate resistor on hand for this,
> > but I will pick one up
> > and give it a try.
> >
> > Could 20 turns of #26 be yet to many turns for the feedback
> > coil?
> >
> > Thanks,
> >
> > Kris
>
>
>
>
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