Re: Inductive Kick Effects - was- Re: cap firing voltage scope measurements question (tests)
A ramp voltage preforms the best at producing Kick voltages but, they
require an amplifier to drive the coils, and eliminate the potential of
using spark gaps in normal fashion.
The gap would have to stop the current through the primary, which would
place the charging capacitor in series with the primary, to a second
capacitor. This would give circuit the appearance of a filter circuit, and
the spark gap would short to bypass the primary to ground shorting out the
bank of capacitors on the current in side.
_|_ | prim _|_
_ _ gap _ _
| | |
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Saturday, June 19, 1999 4:09 AM
Subject: Inductive Kick Effects - was- Re: cap firing voltage scope
measurements question (tests)
>Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>Hi John, Malcolm, Richie, All,
> Well, I finally get it too! Richie sent me an excellent model that made
>the effect simple enough for me to understand too :-)) Basically, the gap
>switching is changing the system from a resonant charging circuit to more
>of an inductive kick charging circuit. It is storing energy in the
>inductor and then the switching action allows a sudden high voltage kick
>right after the gap opens that charges the cap up to a higher voltage than
>the circuit would normally produce. This works much like those power
>supply ICs that switch current across an inductor to get -15 volts from +5
> The real key is the energy that is stored in the inductor when that gap
>fires. I made this table of stored energy in my new LTR coil just before
>the gap fires.
>Neon Primary 24.95 J
>Neon Secondary 23.75 J
>Filter Caps 0.2 J
>Primary Cap 5.97 J
>Primary Inductor 0.0J
> Obviously, the neon transformer is storing an overwhelming amount of
>energy. At only 80 mA across each of it's giant 3700H inductances, a
>secondary winding stores 1/2 x L x I^2 = 11.84 Joules per side!! I never
>considered this before. The computer programs just crunched this factor
>with everything else but I was oblivious to this giant energy being stored.
> The neon is acting much like a current source do to the giant inductance
>and will push current into the cap as it pleases causing the cap voltage to
>skyrocket!! It is possible to get up to 100+ kV if one really tries! Of
>course, the smaller the primary cap, the more voltage the inductor will
>push it to...
> This is apparently the mechanism behind the LTR coil's ability to charge
>larger cap values than one would normally expect. I knew from computer
>simulations that the effect was there but I never really understood why
> Consider this; If a cap were charged continuously at a rate of 60mA, what
>value cap could one charge if the end voltage were 21.2kV? V = 1/C x I x T
> so 20000 = 1/C x 0.06 x 1/120. C=23.6nF which is just what an LTR coil
>with a 60mA neon likes to run! Perhaps this is a governing equation for
>LTR coils given and available RMS current level? Perhaps this can be used
>to very easily calculate what size cap a give power transformer will
> I was hoping this would also explain why some filter resistors like to get
>super hot while others stay cooler depending on yet unknown things.
>However, I don't see how this would explain this mystery... The filter
>resistor's values may be more important in such a circuit than I originally
>thought. Their resistance keeps the transformer from seeing a dead short
>when the gap fires, thus possibly saving the stored inductive energy from
>being lost to the gap... Have to think more on that...
> Many thanks to Richie for helping me to see all this!! This whole LTR
>things just became much more clear but now has added factors to consider...
>At 09:50 AM 6/18/99 -0400, you wrote:
>>Terry, Malcolm, Richie, all,
>>I found my voltage breakdown table, and after interpolating for my
>>voltage, etc., the table shows very good agreement with my scope.
>>Just a further verification of the voltages I'm seeing. It seems from
>>your comments, that the 2X rise is not un-expected. It looks like what
>>I had heard in the past was wrong. Well, the Tesla coiling world is
>>full of myths anyway, looks like I got caught in one this time. I'll be
>>doing some more work with the set up.