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I am new to this great forum, and english is not my first language so please be indulgent.
I have made this post to present and share this project.
The marx gen itself is an 8 stages unipolar model with charging resistors. The capacitors are homemade type with rolled "plastic wallet" and aluminium foil. I measured their capcitance and they all have about 2.3nF. I don't know how many kV they can withstand but they were fine at 30-40kV. Charging resistors are made of three 330k 1W resistors put in series. Spark gaps are bent copper wire. The overall assembly is mounted vertically on a PVC pipe, drilled to hold the long capacitors.
The power supply is a simple 555 and mosfet driving a monitor LOPT, with the quasi resonant mod posted by Dr. Kilovolt (thanks BTW ) I don't know the exact ouput voltage, but it should be arround 20-30kV.
Main spark gap of the marx generator is set to approx. 18cm, and the repetition rate is about 1/second, depending on the first spark gap sapcing. Sparks are loud and bright, but nos as bright and thick as the video and picture show.
I was sure the term "plastic wallet" would mean nothing in english, but at least i tried ! I don't how it is called in english, here is a picture of it :
This is the dielectric. I cut the holes and just keep the plastic sheet, in fact, there are two thin plastic sheet in each one. To make the capacitors, I put two "see the picture above", one aluminium foil sheet with a wire, three plastic sheet, one aluminium foil sheet with the other wire and then to finish, one plastic sheet. I roll this around a small PVC pipe, and secure the whole assembly with tape. So, anywhere in the capacitor, there are atleast 3 "plastic wallet" between each opposite polarity plate, that is to say 6 plastic foil. I also make sure that the aluminium plate have enough clearence to the edge of the plastic sheet to prevent arc over.
I am not sure of what plastic type the dielectric is made, as it is not labelled on the box, but I think it is PP.
So far, I haven't got any failure while running them at 30kV, and they do their job quite well for something that is home made.
The overall cost of this marx generator is about 8$ (I only count the parts that I bought especially to build it).
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
magnet18 wrote ...
generally that's called a divider or separator or something along those lines to be honest I'm not entirely sure of the name myself
I think you are confusing these with dividers. These are like an envelope that you put a sheet of paper inside, to protect it. I think I've seen them called wallets in the shops.
Registered Member #3766
Joined: Sun Mar 20 2011, 05:39AM
Location:
Posts: 624
Ash Small wrote ...
magnet18 wrote ...
generally that's called a divider or separator or something along those lines to be honest I'm not entirely sure of the name myself
I think you are confusing these with dividers. These are like an envelope that you put a sheet of paper inside, to protect it. I think I've seen them called wallets in the shops.
We're also across the ocean from each other, so they might be called different things. I know at my school we usually call them "those 3 ring divider things"
Registered Member #3888
Joined: Sun May 15 2011, 09:50PM
Location: Erie, PA
Posts: 649
how about "page protectors" if you could manage to slide a sheet of aluminum foil inside of them neatly, you could slap two together and roll them as a capacitor.
I am having a minor problem with the marx, and thing that I do not understand, so I ask you guys
My power supply is a 555 driving a flyback, but I am running the Hv side of the flyback ungrounded, I know this is bad, but I don't understand why.
The fact is that if i connect the HVGND of the flyback to the GND of the low voltage side, the marx does not work anymore. It fires erratically, the whole assembly is making a huge corona noise and most charging resistors are arcing over, which is bad. Once I unground the HV side of the flyback, the marx run perfectly well. How is it possible ?
Also, when I run the marx with the flyback ungrounded, each time the marx fires, I can see a small spark at the flyback's bottom, running from the HV GND to the core, even if the whole bottom of the flyback is "sealed" with hot glue. Is it happening because of a high potential running on the HV side ?
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