Re: DSL-Diode Spark Gap Logic

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "B2 by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bensonbd-at-boo-dot-net>

Hi Bert, All,
    I gave a demo this weekend to some local coilers.  We ran the coil for
15 minutes full boar with the same results.  Everyone touched the spark gap
tube as if it would burn their finger.  We were pleasantly surprised to
find that it was barely above room temperature.  I found the (written) data
on the system.

Transformer Voltage = 3 kV RMS
Transformer Current = 30 mA RMS
Lp = 162 uH
Cp = 15 nF
Primary Joules per bang = 0.135
Zprimary = 103.9 Ohms
Ip = 28.9 Amperes RMS
There are 5 x 800 Volt varisters (4000 V) clamping the tank voltage.
Ls = 234 mH
Cs = 4.48 pF
Cs-toroid = 3.99 pF
Fr-system-=107 kHz
k = 0.28

These measurements were made with an HP 5300 A counter and a Tektronics 475
oscilloscope that has only a few useable volts/div settings.

> Hi Barry,
> 
> Interesting experiment! That Spellman primary must have quite a few
> turns, since it clocks in at over 1 mH. And, assuming the gap is
> repetitively firing at 2500 Volts, the bang size is only a little over
> 0.03 Joules and the peak primary current is only about 8 amps. This is
> probably why both the gap and diode aren't being stressed very much. 
> 
> Assuming the diode chain conducts half of the time, the peak voltage
> drop in the diode chain's forward direction will likely be in the range
> of 8-12 volts, while the spark gap's conduction voltage (assuming fill
> gas is air) would be in the range of 150-200 volts (or about 10 times
> lossier). Given that the heating of the diode chain is shared across 8
> diodes, the relative temperature rise of a given diode versus the spark
> gap (due to I*E losses) sound about right. And, in theory, the overall
> "lossiness" of the gap should be less with the diodes connected across
> it versus alone.
> 
> Did you notice any performance improvement with the diode chain
> connected versus without?
> 
> Also, what kind of performance did you see either way (i.e., spark
> length)?

The sparks seem to be much longer but dimmer with the diodes connected.
When time permits I'll do a side by side experiment.

> 
> Thanks, and best regards,
> 
> -- Bert --
> -- 
> Bert Hickman
> Stoneridge Engineering
> "Electromagically" (TM) Shrunken Coins!
> http://www.teslamania-dot-com