I built the Marx generator about 3 or 4 years ago before the price of the
30Kv capacitors got to today's higher price. Started out with two towers
of 10 stages each and that worked so well that I added 5 more stages to
each tower. In the beginning I did have some problems with my charging
system which I overcome with added protection circuitry. It fires about
once every 5 seconds with the power supply set at its maximum voltage.
Also built a small dual tower unit with small disc caps that produces about
a 1ft spark. Just wish there was a source of less expensive HV caps and
I'd try for a larger set of towers. Charles
On Sat, Jun 23, 2018 at 6:38 AM, David Rieben <drieben@xxxxxxx> wrote:
> Charles,
>
> Wow! 36” spark! That’s impressive. I happen to have a surplus x-ray
> transformer (with its internal diodes still intact) that I currently
> already have set up to be fed with the current ballasted 0 - 280 VAC output
> from my large Tesla coil control panel that would serve admirably for
> feeding a ‘man-sized’ Marx generator. I have toyed with the idea of
> building a big Marx bank before, but the challenge of its sound
> construction, both from an electrical as well as a mechanical standpoint,
> the unlikely prospect of procuring all of the required matching HV Caps and
> resistors on the surplus market and the consequential cost associated with
> obtaining the same on a retail market, and the total lack of space to
> safely operate such a beast have pretty well placed that project on the
> back burner for now. :-/
>
> David
>
> Sent from my iPhone
>
> > On Jun 22, 2018, at 8:26 PM, charles rakes <crakes29@xxxxxxxxx> wrote:
> >
> > I use a 15Kv 60ma NST with 30 diodes in series on each output hot
> > terminal. One string with a negative output and the other with a
> > positive. I get over 22KV DC output that I use to drive my dual 15
> stage
> > Marx generator and get about 36-inches spark between the two towers. The
> > NST's primary is controlled by a variac.
> >
> > On Fri, Jun 22, 2018 at 2:14 PM, Matthew Sweeney <msweeney23@xxxxxxxxx>
> > wrote:
> >
> >> Hi Raymond, I did this using strings of cheap Microwave oven diodes
> potted
> >> in short PVC tubs with paraffin wax. I also added some high wattage 1M
> >> resistors for my own safety.
> >>
> >> Basically I created large, clunky, cheap 30KV-50KV diodes :)
> >>
> >> It worked well, but I think the diodes would be better off in epoxy
> >> specific for the context. Rectified DC off an NST is a different beast
> and
> >> kinda scary for me :)
> >>
> >> I was using this to drive a VDG, but the voltage was too high and it's
> very
> >> much overkill!
> >>
> >> Good luck!
> >>
> >> On Fri, Jun 22, 2018, 5:35 AM Raymond Spigot <
> raymond.j.spigot@xxxxxxxxx>
> >> wrote:
> >>
> >>> Hi, thanks for all the interesting discussion about NST testing and
> safe
> >>> grounding, it's all been instructive for a noob
> >>>
> >>> I have this grey resin block neon transformer in the shed I was
> thinking
> >> of
> >>> experimenting with. It's a 15kv/30mA one with a midpoint ground
> >>> connection. Is there a way to rectify the output so I can use it for
> >>> trying out powering a dc tesla?
> >>>
> >>> I have a big bag of diodes (1N5408 I think) that were pretty cheap. If
> >>> they'll handle 1000v each I could solder them up into long strings and
> >> use
> >>> 4 strings of diodes to make a bridge rectifier? I guess I'd need a
> >>> capacitor on the other side of the bridge as well though to smooth it
> >> out a
> >>> bit.
> >>>
> >>> Then I was wondering if there was another way to do it with a midpoint
> >>> grounded transformer like mine. I'm thinking the 2 secondary windings
> on
> >>> the transformer must be out-of-phase, but could I rectify them
> >>> individually? Between each HV output and the midpoint ground I mean.
> >> Then
> >>> I'm thinking I'd need 2 bridges but they're only trying to rectify half
> >> the
> >>> voltage each and it would be easier to cope with.
> >>>
> >>> Basically I'm hoping there's a way to get like 10kv dc out instead of
> >>> closer to (I think) 20kv Because then I can buy a main MMC capacitor
> >> that
> >>> doesn't have to be rated for the highest voltage (so I can put less
> caps
> >> in
> >>> series)
> >>>
> >>> hope this makes some sense to someone! thanx for advice anyway
> >>>
> >>> Ray
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