Neons and Sync Gaps
From: Bert Hickman[SMTP:bert.hickman-at-aquila-dot-com]
Reply To: bert.hickman-at-aquila-dot-com
Sent: Thursday, September 25, 1997 9:04 AM
To: Tesla List
Subject: Re: Neons and Sync Gaps
Tesla List wrote:
> From: Jason Judd[SMTP:Jason.Judd-at-anu.edu.au]
> Sent: Wednesday, September 24, 1997 10:49 PM
> To: Tesla List
> Subject: Re: Neons and Sync Gaps
> Hi Malcolm and all,
> I am starting to think that the voltage at which a static gap fires at has
> almost nothing to do with the gap distance. Last night I installed another
> 15 Kv 30Ma neon in my setup giving me 15Kv at 90Ma. With a smaller gap I
> was able to get 3' sparks like before, but now they are really powerful
> white hot arcs as well. When I removed one neon the sparks were only 2 foot
> and thin again. All the neons have been tested together and individually
> and are fine.
> I would assume that the capacitor voltage before breakdown is the same and
> hence the stored energey would be the same. So why am I getting a 33%
> increase in spark length and sparks that are at least twice the diameter. I
> would estimate that there is between 50 and 100% more power in the arcs.
> Even with 2 neons and the gaps set much wider I don't get sparks any where
> near this quality.
> At no time under any setting has my gap failed to fire.Primary cap is 14.3
> nF. I have not measured the input current , but that is next on my list.
> > BTW, the unpotting is a horribly messy business. However, I'm
> > indebted to Richard Quick for the information he provided which gave
> > me the inspiration I needed.
> > Lastly, the gap distances and known o/c peak output voltage of
> > the transformer suggests the 35kV/inch rule is a very useful guide
> > for these sorts of distances.
> > I am going to place a caveat on this. I regard the above guide as
> > true for sharpened wire ends. However, nice rounded electrodes should
> > have this figure doubled IMO. I think based on observation (plus
> > information from Glasoe and HPE) that 70kV/inch is far more realistic
> > for a typical gap electrode. In other words, if you static gap is set
> > at 1/2", you are probably firing at 30kV+ so watch those transformers.
> I think I will head your advice on this and am glad that I have not killed
> any neons yet :-)
> It would be interesting to watch the tank and gap voltages on a scope and
> see just what is happening. Has anyone done this or have a good way of
> doing it ?
> > I have Jason in mind while saying this. According to this then, my
> > setup was firing at around 17kV which was the o/c peak transfromer
> > voltage. Sorry for equivocating once again :(
> > Malcolm
The voltage breakdown repeatability of a series spark gap is generally
quite good - typically within 5% once it has stabilized, so your "bang"
(i.e., the amount of tank capacitor energy available when the gap fires)
will be fairly consistent. However, when you add the additional trannie,
your tank capacitor is now getting recharged much more quickly. The
effect will be significantly greater than just 50% (60 to 90 MA) since,
if you're running off 60 Hz, you're also approaching 60 Hz resonance
between the effective inductance of your trannies and your tank cap.
This allows your neon bank to supply signifiicantly more than 90 MA or
capacitor recharge current.
The additional current more quickly recharges your tank cap to the gap's
firing voltage so that your gap now fires more often during each half
cycle of incoming power. The output power of your coil is directly
related to the number of "bangs" per second. Under these conditions,
merely adding the new trannie may effectively result in a 100%-200%
power increase (or more) for your system. That's GOOD news. However,
don't open your gaps too widely now, since this resonance condition can
also cause your transformer output voltage to soar to self-destructive
levels if not "clamped" by reasonable gap spacing or by an auxilliary
safety gap (if you use filtering between your trannies and the gap...).
Safe coilin' to you, Jason!
-- Bert --