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Registered Member #4187
Joined: Fri Nov 04 2011, 08:08PM
Location: Spain
Posts: 43
Hi,
I completed an 11 stage Marx supplied by a 8kV NST with half wave rectifier.
With just the NST I tested arcing distances with 14mm gap (with rounded tips) or 17mm gap (pointy tips). I used about this distances for tuning the gaps in the Marx.
System is like this: NST + Terry filter (from a Tesla coil I made, as protection)- 3x 2.7M with 2x diode 10kV in series - 11 stage Marx with 1nF caps and 3x2.7M resistors.
Charging to 9-10kV peak should be complete in about 4s according sims:
As a first test I fired it with just the 2 initial stages, and without the first 3x2.7M resistor (because I forgot to add it). It worked. With the 11 stages however it doesn´t fire.
Now I put the initial 3x2.7M resistor in place to have the usual Marx circuit, and I can not fire it, nor with 2 or with the 11 stages.
I just get some minor sparking when I bridge the gaps manually with a wire. The caps seems charged (they spark noisily when bridged, see video) http://youtu.be/uyKOpbpv4Ts
Don´t know well what´s happening, please any help will be welcomed.
Registered Member #4187
Joined: Fri Nov 04 2011, 08:08PM
Location: Spain
Posts: 43
I did some measurements and voltage drop in the resistors seems ok, about 200V in total for the 11 stages. Diode is OK so in voltage terms all seems ok.
I repeated the test and I got to fire it with 3 stages and removing the first step loading resistor. With more I just get some minor arcing (like corona discharge) when I put near a wire to close the first gap, but not a sudden discharge spark.
Might be that 1nF is too low cap to fire properly?, any idea will be welcomed
Registered Member #4497
Joined: Thu Apr 19 2012, 12:53PM
Location: Behind you
Posts: 62
> reduce spark gaps to 3-4mm, first one should be smaller than others > resistors could be better 1-1.5M, but I think it will be fine > try reduce main resistor to 2-3M, it could help
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Marx not firing, please help
