Here’s my man sized Marx that I built on the cheap using plastic spring water bottle caps and adhesive aluminum tape.
1-2 feet sparks easily.
I used PVC pipe and styrofoam insulation for the support. I cut down on the amount of wiring by using one surface of the water bottle caps as a discharge electrode for the Marx.
This uses strings of 6 x 333kHz series connected resistors for each stage of rye Marx. The strings are covered over with shrink wrap to reduce corona losses. The setup is powered with a 20kV CW multiplier powered with a 2 kV 20kHz AC gas lamp supply.
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> On 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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