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Registered Member #1223
Joined: Thu Jan 10 2008, 04:32PM
Location:
Posts: 133
Just get some cheapest possible small ceramic disk capacitors, like 1nF/10kV..more or less depending on your needs. And some HV resistors ofcourse, 1..5Mohms should be ok (you can also use smaller resistors in series to get enough voltagerating).
My previous 10 stage marxgenerator was using 1nF/15kV ceramic capacitors and 2Mohm resistors. Sparklength was about 25-30cm. As a powersupply, I used NE555/single mosfet circuit and AC flyback/voltage tripler (cascade from TV) combination.
Registered Member #690
Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616
I want to emphasize the fact that you need to have adequate voltage-rated resistors. I have had many large 2 Watt 1Mohm resistors die in a ZVS-powered marx configuration. They all died open-circuit.
I assumed that their large physical size and high power rating meant they could take higher voltage without flashing over. Although they didn't flash over, I now use at least 3 in series, or some real HV resistors (the tiger stripe kind)
Registered Member #690
Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616
Those resistors are exactly the same type that failed for me. They may work, but not reliably.
I would try these: They cost a little more, but you get 24 of them. They are only 620K, which will probably work on its own. If not 2 series will do it.
As for capacitors, those will be fine but you may want to check Ebay for them too, as you can usually find groups of them on the cheap.
Registered Member #690
Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616
Okay, but they are only rated to 500V each.
Since resistors are such a pain, you may want to consider trying an inductively charged marx generator. The operating principle it the same, but you replace the resistors with homemade inductors, which IIRC are about a hundred turns of thin magnet wire on something the size of a drinking straw. I can't find an example, but I'm pretty sure someone here has built one. Maybe they will chime in?
You can get VERY fast rep rates with inductive chargers, due to their very low DC resistance.
Registered Member #180
Joined: Thu Feb 16 2006, 02:12AM
Location: Ontario, Canada
Posts: 187
If you were to wind the wire over a resistor I'm going to bet you won't be able to add enough turns to get a high enough inductance. It's kind of like shorting the resistor out, unless you can squeez enough turns onto it.
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Marx Generator
