Re: DSL-Diode Spark Gap Logic

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

Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>

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)?

Thanks, and best regards,

-- Bert --
-- 
Bert Hickman
Stoneridge Engineering
"Electromagically" (TM) Shrunken Coins!
http://www.teslamania-dot-com

Tesla list wrote:
> 
> Original poster: "B2 by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<bensonbd-at-boo-dot-net>
> 
> Hi All,
>     I am about 1463 e-mails behind at the moment.  Classwork will limit my
> reading until December.  In the mean time, I had a free 30 minutes for
> experimentation.  I tried the following:
> 
> 1. Transformer is 4 kV, 30 MA bug zapper transformer.  Transformer HV
> output is connected to the tank capacitor via 5 KOhm-50 Watt resistor plus
> two 6 kV diodes (All Electronics) in series (12 kV total).
> 2. 0.01 uF MMC.
> 3. Resonant frequency-50 kHz.
> 4. Primary and secondary are from an ancient Spellman HVPS.
> 5. Secondary is pie wound-10 pies-4 inches winding length.
> 6. Victoreen-DSL-SGCA-2500D precision spark gap (fires at 2500 Volts within
> 5 %-Haven't found another source) paralleled with 8 series connected diodes
> (1N5408-1kV-400 Ampere surge-All Electronics, Digikey).
> 
> Notes:  Fired the coil for 1 minute.  Unpluged it and then shorted out the
> MMC.  Touched the SGCA-2500D and diodes.  They were both barely perceptable
> warm.  Under normal operation the SGCA-2500D would be too hot to touch
> after 30 seconds.
> 
> Theory:  The SGCA-2500D conducts for only 1/2 cycle.  The diode string
> conducts for the other half cycle (extrapolation from Terry's research).
> 
> Comments: It is interesting that such a low frequency diode works at 50
> kHz.  More experiments at higher power as time permits.  Interesting
> possibilities here.
> 
> Cheers,
> Barry