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Registered Member #75
Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711
He was talking about "diposable camera capacitors" so while the output of the generator might just be in the kV range, the input certainly wont be. Here is another idea though:
MOVs (Metal Oxide Varistors) have a polysilicon junction and are a great deal more robust than ordinary semiconductors. They could easily cope with the pulse loads of this type of marx generator.
Depending on the SIDACs you have (do you have a part name?) they might be able to cope aswell, so why don't you give it a shot.
Registered Member #690
Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616
Okay, here's an idea. As Sulaiman said, Xenon flash tubes would make good high current switches as they self-trigger and can carry high amps.
However, they are designed to dissipate as much energy as possible as light, I know because once I tried to make a silent SGTC gap from a bunch of them in series; they just heated up fast with only mm arcs from topload. You can't quench them w/ air, so I used NIB magnets, but thats another story for a different thread.
But sadly, they trigger at far too high a voltage to be useful for triggering photoflash caps. Now I'm going to assume that if a Xenon bulb is capable of such high amps, then so is a Neon. In the very same camera flash board you probably harvested your capacitors from, there is a "flash charged" indicator lamp. I think newer ones use LEDs, but all mine are small LED-size Neons that trigger at exactly 270 volts. Why 270? I have no idea.
Try desoldering some of them. They just might hold up in such a low-voltage Marx circuit. Or they could explode. Either way, you will at least get one shot .
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
What's wrong with SCR's? You can cheaply get TO220 SCR's capable of several-hundred amp pulses. Still, I think you would need some kind of pulse forming inductor on utput to keep them from blowing up. SCR's of same rating are orders of magnitude cheaper than sidac's.
But, If you really don't need to be able to trigger it externally I think you'l be equally as happy with CW multiplier. Diodes are again much cheaper than SCR's.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Firnagzen wrote ...
Hey, we just didn't want you to blow your SIDAC's for nothing. I really don't think their peak rating would suit the electrolytic caps short-circuit discharge.
They take very high current hits especially in single shot. They are just tiny things, but when they turn on, they really mean it!!
Firing a long string gets odd... The SISG turns on from current in the whole string so that is controlled. But SIDACs are real tough and they might do just fine in a Marx configuration. My guess is they will do fine.
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SIDAC Marx?
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