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Re: marx chokes

Original poster: "Dr. Resonance" <resonance@xxxxxxxxxx>

Thanks for the data.  Do you recall the approx number of turns of wire per
choke, and also approx wire AWG?

As an EMP generator, sounds like it was very efficient.

I look forward to seeing some photos when you get time.  No rush, I don't
return to my lab in WI until the middle of May.

DC Cox

Dr. Resonance

> > Hi DC, > From memory it was several mH per choke. For the first > machine, I used 0076-type PVC-coated hookup wire wound in three > layers over a rod about 1/4" in diameter and about 5" long. Each > capacitor was a homerolled dry-fired poly/foil cap wound as per the > recipe in my article except that there was no acrylic former in the > centre. Each was about 5 - 7 nF as I recall. The machine is difficult > to describe but was designed to be as short as possible for the > voltages to be developed. The tower formed (looked a bit like a > highrise) was about 20" high, maybe a bit more. > Each stage was sandwiched between two acrylic sheets with two > thick lumps of acrylic to generate the spacing. The gaps were formed > from heavy copper wire. It is really difficult to describe. I did > take some pictures though. I'll have to wade through rolls of > negatives and get some prints to scan. It would be much easier to see > than describe. The first machine had about 20 stages and the second > had 22. The chokes for the second machine were made using the same > rods but with a single layer of polyesterimide wire wound over a > coating of insulation tape and the inductance was lower. The first > machine worked better and reflected the higher choke inductance and I > think would have worked better if the inductance had been higher > still. It was charged using a flybaack cap charger (my test EHT > supply) to about 15kV/stage before it erected. I used no triggering > gap but it wasn't difficult to adjust the gap spacing so it worked > reliably. I got the idea after trying out the Blumlein switch shown > in an old Amateur Scientist article which showed it being used in a > pulsed UV laser. I later procured a copy of Sargeant and Dollinger's > "High Power Electronics" and saw that my "novel" design had been > thought up and developed decades earlier. I will get some pics > sometime over the next week and ask Terry nicely to put them in my > little corner of his website ;) > > A word of warning - first light was a great success but resulted > in my spending the next three days repairing a variety of equipment > which had been taken out in the workshop in which I tried it. I think > the main problem was inadvertently applying high amplitude step > functions to the mains ground but I wouldn't be afraid to take a bet > that it wasn't a bad EMP generator in its own right. Thereafter > running was confined to a physics lab. The topology of the structure > resembled a helical antenna with gaps forming a spiral in one > direction and chokes forming a spiral in the other. I can only guess > at the electrical mayhem that went on when it erected. > > Malcolm > > On 11 Apr 2005, at 23:18, Tesla list wrote: > > > Original poster: "Dr. Resonance" <resonance@xxxxxxxxxx> > > > > > > > > Malcolm: > > > > What was the value of your chokes? I would like to try this idea as > > well. Digi-Key stocks a large number of iron core chokes. > > > > Dr. Resonance > > > > > > > > > > > > > Use chokes instead of resistors. The benefits: much faster and more > > > efficient charging (far less resistive loss). As to the values, > > > mileage varies. There is balance between charge time and sufficiently > > > high impedance at discharge time. I built two working Marx banks, > > > both of which used chokes wound on ferrite rods. I spoeculated at the > > > time that suitably sizing the components might allow resonant > > > charging at mains or some other nominated frequency but pursuing the > > > idea is way down my list of things to do. > > Malcolm > > > > > > > > > > > >