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FW: DC coil?



 
Hi Benjamin,

9kV at 30mA from 12dc would be great, 
IF it can do that continuously.

Let me and the list know the your results.

More likely it is a converter that is designed for much less 
continuous output Voltage, typical for solid state replacement
for the "NST" but capable of running only at ~1kV at 30mA continuous 
after a trigger pulse of 9kV which ionizes the neon tube.

Two investigative approaches:
1.) Find a spec sheet or inquire as to exacts specs from the mfr
2.) Set up bench test (suggested anyway to verify mfr statements/specs)

I you have the converter, run some bench tests. 
Required is a large likely custom HV load resistor.
 
Rload=9kvrms/.03= 300,000 ohms with
power = .03*9000= 270W so you need substantial heat dissipation capability.
like 10ea 30k 30W, or 30 ea 10k 10W  etc.

If you can attach this load and the measure 9kVrms you are in business !!
(and we want to know where to get them, i.e. distributors, cost, etc.)

Note that this measurement may not be easy. 
The converter output probably switches at high frequency (~20kHz) 
to keep the size and weight (inductor) down.
If one side of the converters HV output is ground referenced (unlike 60Hz xfmr)
the load current may be more easily instrumented - 
measure the voltage across a part of the load. 3k = 100:1 so you'd expect 90V 
however response time becomes an issue.
High frequency reactance upsets the divider, and the need for compensation
network
adjustment such as oscilloscope probes use.

If you use a fast HV rectifier, conversion to DC (averages) removes the
frequency problem.

Expect a much lower like output, like ~1kVrms with period(s) of HV pulsing.
Be pleasantly surprised if its 9kVrms !

There are individuals on this list with SS Ballast with hands-on 
knowledge and experience which I do not have (speaking from what I've read).
---------------------
I have a low power battery powered low bang rate DCTC using a flyback
converter from 12v.

---------------  FYI !!!
My single shot battery powered 1 watt DCTC:

Single shot Arcs over hard (non arc participating) dielectrics restrict
discharge to 
2 dimensions increasing statistical probability of producing a max length
power arc.

Current Specs, performance:
Ctop ~25pF 8" x 20" galvanized toroid
Lsec 30mHy 6.5" dia 20" long white PVC form
Lpri 3.4uHy 1/4" Cu tubing, spiral, 16" OD (tap outside in)
mutual coupling coefficient adj .18 to .22
Cpri .2uF 10kvdc 4.9J per bang
Vpri 7kVdc via 12v dc-dc flyback converter from 1.5" BW video camera
monitor, 50mA quiescent
GAP = commercial Jennings/Kilovac vaccum relay implementing unique 'jog' method
Vout-pk = Vpricap * sqr(Lsec/Lpri) * efficiency
Vout-pk = 7000 * sqr( 30mHy / 3.36uHy)*.8 = 529,150 Vpk (theoretical maximum)

Power Discharge point to point maximum to date (7/4/00) = 38"+ 

Easily scaleable up or down (add or remove .1uF caps, adj Pri tap)

Arcs are generated in front of hard dielectric: glass, plastic, masonite, 
(dielectric does not participate in arc gases as evidenced by it visible
spectra = that of N2, O2)
to encourage arc path to 2 dimensions (Vs 3 dimensions in the dielectric
Air, 78% N2, 21% O2)

original DCTC picts: 
.1uF 7kV 2.45J
12v to 7kVdc converter, Sparks, scope field V & Iarc waveforms, trick or
treat '99 photos:
photos: D300 Olympus 1024x768 and a calibrated button finger 
(capture ~1 of 8 due to "no bulb" on digital cameras)
see photos of components & arcs:
http://www.cowmail-dot-net/dalehalldctc/

enclosures: more recent 38" discharges

BTW: the DC-DC converter can be designed for higher current (or V) output
which can  
drive higher BPS (alternate gap design) at the cost of complexity, cost and
input power.

Regards, Dale 
Redondo Beach, Calif.
dale.hall-at-trw-dot-com

http://1071737050/site/TCList/09balPwr%2B2branch37inGud.jpg
http://1071737050/site/TCList/12balPwr%2B3br35inGud.jpg
http://1071737050/site/TCList/15balPwr37in.jpg

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com] 
Sent: Sunday, July 30, 2000 9:44 AM
To: tesla-at-pupman-dot-com
Subject: DC coil?

Original poster: "Benjamin Ness" <bness-at-home-dot-com> 

Hello all,
 
    I am a 16 year old coiler, so far I have built a small TC using a 12/30 NST
(this won me third place in a national science fair competition this year!),
and I am working on a 6x30 coil powered by a 9/60 NST.  However, I also
stumbled upon a possible source for a portable DC coil:  A neon transformer
designed to power underbody neons on a car.  Input is 12 v DC, output is 9000v
30 mA, I'm not sure if it is AC or DC, I have to check it.  But if it is DC,
what changes would I have to make to the primary circuit?
 
Check out my webpage at <http://fly.to/budspage>http://fly.to/budspage
 
Benjamin Ness