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Registered Member #1408
Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679
I had wondered if anyone had found a more consistent method of making a spark gap for a Marx generator? That is, some pre-manufactured or substitute format to replace the "DIY wire style" spark gap so that consistency could be maintained as well as a degree of ruggedness.
My other question pertained to a Croft Walton design. I had read of some folks using a resistor to protect the components and found this: Is there a formula & / or reason why the use of a resistor would have benefit (safety issues in grounding, etc)in a three or four stage CW? Or is this simply to lower current levels to match capacitive strength?
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Dome head nuts are available all the way up to M24 and probably even larger than that.
Since they are mounted at the end of a machine screw, you can adjust your gap to a high degree of precision, and then lock it.
As for the C&W output protection resistor, it is there to ensure that a catastrophic discharge doesn't exceed the surge current rating of costly diodes. Its value is chosen so that a direct short to Earth at the output voltage doesn't exceed the diodes' maximum surge current, a simple Ohm's Law matter.
Registered Member #1408
Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679
I appreciated you taking the time. I have seen so many designs that used some fairly high priced diodes, that I thought perhaps there was a realistic answer to protecting them. I'm not sure what you fellows get at Farnell's but in the States, even if we have a company buy for us, many places are just outrageously high priced on HV diodes. Many of the "specialty HV firms" are particularly over priced.
The Dome Heads are a great idea; I may just give it a go. I never mind putting work into something if it will last. Bending small wires to make a gap seems like the Legend of "Sisyphus & the Stone".
Registered Member #1221
Joined: Wed Jan 09 2008, 06:17PM
Location: Odense, Denmark
Posts: 196
I used 3mm "dome heads" for a 14 stage marx, it wasnt super stable but its sure nicer than wires. My avatar is one of the discharges from that marx generator
Registered Member #1408
Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679
@GLuD: That is a cute shot. I'm determined to make something that's stable enough to not be a fragile "one-time-wonder.
@radhoo; I like the way you used the simplified ZVS schematic. My design will most likely be very similar.
I would like to mention that I got my order from OT ELECTRONICS (they ship all over the world and their prices are what I've been VERY happy with! I really recommend them as they have all the needed parts for CW multipliers & have beaten the pants off most places in the United States in costs for small orders. So it's the same shipping for Europe as the USA.
Registered Member #1221
Joined: Wed Jan 09 2008, 06:17PM
Location: Odense, Denmark
Posts: 196
Heres how I did it
As I said its not super stable, but I suspect thats because I didnt take the time to tune the bolts and "dome heads" finely enough, plus I dont have active triggering, it just shoots off whenever theres enough volts to jump the first gap. I wouldnt call it a one time wonder, although the picture was (almost), took over a hundred photos only two had sparks in them.
Registered Member #1408
Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679
Makes me jealous enough to start one! I love the durability. I've made several but they always would up in the "de-solder drawer". This time, I'm going to make a "keeper"!
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General questions re: Voltage multipliers
