Re: [TCML] Using Triggered Gaps, was Designing a Coil Around a SRSG

[Futuret <futuret@xxxxxxx>]

I experimented with two methods that used an automotive
ignition coil to trigger the cap using a centrally located
tungsten rod placed halfway between the main static gap.
One method supplied voltage to the ignition coil to create
the HV pulse, the other method removed voltage from
the coil to create the pulse (inductive kick).  Both methods
worked and I controlled the timing using a lamp-dimmer
type triac/diac phase controller to time the spark.  (I used
phase angle to trigger time-wise, not voltage.)  Both
methods were a little touchy to adjust and were at the
edge of their ranges for best results.  This was based
on work that Mark Metlica did years ago, and John
Tebbs also did some designing on the inductive kick
method if I remember correctly.  This work should all
be in the Pupman archives.  I had to set the main gap
about 5/8" to 3/4" wide to prevent premature firing 
using a 12/30 NST.  I did these triggered static gap
tests using my TT-42 coil which normally ran with a 
120 bps synchronous rotary gap.  

   Jim wrote:

"On this basis, one would expect a single triggered gap with long path to be 
better than a multigap."


I agree.

Cheers,
John Freau





 

 

-----Original Message-----
From: Scott Moseley <scott@xxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Sat, Mar 23, 2013 11:34 am
Subject: RE: [TCML] Designing a Coil Around a SRSG


Has anyone come up with a  good electrically triggered gap yet?  Maybe something 
that uses magnetic quenching?  If so, then you could sense the voltage across 
the cap, and then set a firing voltage.

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of 
Jim Lux
Sent: Saturday, March 23, 2013 11:31 AM
To: Tesla Coil Mailing List
Subject: Re: [TCML] Designing a Coil Around a SRSG

On 3/23/13 8:12 AM, Futuret wrote:
> contributes to longer sparks.  It is possible to achieve just as good 
> results using a static gap, but it has to be a triggered static gap.
> Interestingly, in my tests, the triggered gap was very loud and bright 
> due to the wide gap spacing which had to be used to prevent premature 
> firing.

  All this noise and light didn't noticeably reduce the spark length
> however, as I obtained the same spark length in both cases.

I think this makes sense.  The voltage drop (loss) across a gap is a combination 
of the 50-100V cathode drop and then the ohmic loss in the spark itself. For a 
reasonably high current arc, I'll bet the ohmic doesn't change all that much 
between, say, 3 and 10 mm.

On this basis, one would expect a single triggered gap with long path to be 
better than a multigap.

Somewhere back in the archives, I know this has been discussed..
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