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Registered Member #75
Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711
nice setup, but I can almost smell the corona that you get from all those exposed sharp edged Did you only run it at 10kV so far or did you try pushing it to the limit of the 30kV caps?
Registered Member #229
Joined: Tue Feb 21 2006, 07:33PM
Location: Romania
Posts: 506
I didnt push it yet at the maximum voltage (short resistors and some breakdown along them). I am waiting some new longer res. Yes, there are sharp edges, i can insulate them with plasticine. I have to tinker a bit. What would be the maximum spark for this setup? 20 cm sparks? I think it is the safer level.
Registered Member #229
Joined: Tue Feb 21 2006, 07:33PM
Location: Romania
Posts: 506
My longer resistors didnt come yet, but I gave it a new push with some sligthly longer 9M1 resistors, covering the sharp edges and with higher input (still 60% of maximum, more voltage = breakdown along resistors). 13-14 cm sparks, pics on the page.
Registered Member #229
Joined: Tue Feb 21 2006, 07:33PM
Location: Romania
Posts: 506
If I would use inductors instead resistors, how much inductance would be necessary per stage (minimum) to be in the ballpark? The coils can be air cored? I remember Steve Ward demonstrated such a setup at the thon. Some tips please?
Registered Member #146
Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055
Inductors:
the inductors used on our marx generator were actually small ignition coils (well, not quite, they were really "magnetos") without a primary winding, and with the iron cores pressed out. They measured 4 HENRIES on my LCR meter, and only a few K ohms (assuming my meter worked properly with the high inductance). The higher inductance forms a lower oscillatory frequency for the output discharge, which allows for more jitter in the system before performance degrades significantly.
I later attemped to replace these magneto coils with my own home wound inductors. With a 2.5" PVC pipe and about 4" of 36awg winding, i did get some results (only a 3 stage marx was built). But, the output was not as long as when using the magneto coils, or resistors. So the inductance wasnt enough with this set up, so i decided it just would not be worth the effort to wind my own inductors in this manner. Perhaps adding a ferrite core (encapsulated in epoxy for insulation) to the inductors would help by increasing the inductance by a few times over, but the amount of ferrite needed would get to be more expensive than the price of the magneto coils, so once again i dumped the idea.
Registered Member #195
Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111
I used two 2 watt 750k resistors I found them on ebay. This is one of two units that eventuly will put out about 1.5MV when added to gether. My picture is a video capture, can any body tell me what they do to catch a digital picture of the spark
Registered Member #146
Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055
My picture is a video capture, can any body tell me what they do to catch a digital picture of the spark
Since my marx fired with a relatively consistent period, i was able to capture pics using my camera with a 1 second exposure time, though even still it was "hit and miss".
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Little Marx gen
Did you only run it at 10kV so far or did you try pushing it to the limit of the 30kV caps?
