Safely testing 22 kV capacitors

It's only a flesh wound?

Snarl

According to Ignoramus27098 :

[ ... ]

You can make 30KV from a single 1KV 60 HZ transformer, with enough diodes and capacitors. The basic circuit of a voltage multiplier is:

(AC)---+--)|-+------+--)|--+-----(DC) | | | | \---/ --- \---/ --- \ / / \ \ / / \ --- /---\ --- /---\ | | | | (G)-)|--+-----+-)|---+------+

That one is enough for a 4X multiplication of the voltage. Keep adding pairs of diodes and capacitors and you keep adding voltage multiplications -- and losing current capacity.

1 KV AC is 1.414 KV DC peak, times 4 gives you 5.656 KV just with this simple circuit. At work, we used fairly small assemblies potted in epoxy to get 45 KV (three 15KV taps from a 1KV P-P input.

But -- it might take nearly forever to charge your caps.

Enjoy, DoN.

You can't get more high-impedance than the electrostatic voltmeter which I posted a link to last night. (Probably the auction is closed by now.) But that kind of voltmeter would allow monitoring the voltage real-time until you decide that it is now time to discharge the capacitor.

Enjoy, DoN.

Well, it's pretty hard to argue with that scenario.

I work at a similar facility and will have to see if they are doing the same sort of thing. Just the other day a Hardinge bed was sitting outside waiting for disposition of some sort. The stuff that gets thrown out there would make a die-hard scrounger cry, though most of it is probably entirely used up.

Mike

your 9KV xformer with a pair of diodes will give you 18KV (standard

1/2 wave doubler circuit) which you apply to third cap, measure leakage with milliampmeter.

offer to the tesla coil commuity - there is a nice listserv for tesla coilers (you'll need to search it out, I subscribed so long ago I don't remember how I found it) - try pumpan.com since that's where the list gets sent out.

suitable diodes are in a Microwave oven, just put two in series

22 KV is not particularly high, but as others have pointed out, you can get a pretty nasty shock -

there is also a tesla ring - follow it

giant snip Bill

to contact me, do not reply to this message, instead correct this address and use it

will iam_ b_ No ble at msn daught com

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On Fri, 31 Mar 2006 12:54:42 GMT, Ignoramus27098 Gave us:

Yeah. Those caps have a very limited number of pulse cycles where they are guaranteed to maintain their rated specs. After that they are typically swapped out of a system for new components. The old ones get used in the lab or get sold as a lot. That is very likely what those are.

Maybe Ignoramus is within his rights.

But Win has a very good point. In any event, if Ignoramus alienates Win and just a few other knowledgeable regulars here, his (Ignoramus's) experience will be badly degraded.

So he may want to think seriously about Win's protest.

--Mac

Thanks DoN. I think that I will just make a 13 kV charger with my 9 kV AC source and a diode.

i

What is worn out for some people, is treasure to other people...

i

Thanks Bill... i

Hm... So... DO you think that they are now useless, or simply a little out of spec?

i

I worked in a medical laser research group. We had 2u odd caps @ 10kv+ as part of a home brew laser supply. Before working on it we'd double check the caps were disharged in case the discharge resistors had failed.

A couple of PVC pipes 2m long with a 12" length of heavy neon sign cable linking them, a couple of M4 screws were stuck through the ends.

When the caps were charged it was like a gun going off - very sharp bang, it usually bought people out of offices all down the hallway. You never stood behind whoever had the rods in case you got a reacting elbow in the face.

r.

On Sat, 01 Apr 2006 13:17:21 GMT, Ignoramus26172 Gave us:

They are probably fine. The spec is there so that the original purchaser knows what to expect from them at their rated specs. They are likely slightly lower in value, but they probably don't have any holes punched through them, since they get used in systems where they are used within their voltage spec.

They may be slightly off their original mark, or they my be right on the money. Either way, maxwell makes some of the best HV pulse caps in the world.

Thanks Roy. That's encouraging. I will try to get appropriate HV equipment and then will test the caps. I may keep one for myself.

i

I was thinking of that, actually. Iggy, what would you need for some of these?

The Wayback Machine

will have the old version of the site, of course.

Just think if those Win and those other people got fed up and had Goggle remove all of their archived posts? Then the archives would be nearly useless. All that would remain would be newbies asking incomplete questions, flames, and idiotic remarks.

On Sat, 01 Apr 2006 15:57:14 GMT, "Michael A. Terrell" Gave us:

There was a time when they archived regardless of the flag setting.

With all the money google has, one would think that they would have several hundreds of terabytes of archival data online and available. One would think they would have other service providers using their servers as the master archive.

That is still no excuse for a poorly planned web interface to Usenet.

I think that I would need all my caps, and some way to vent the copper gas from exploding copper coils. In other words, too violent for me.

I want to keep one or two caps at most. I think that I could build a coke can crusher (you can do a google search for "can crusher capacitor"), using materials readily available, such as solid copper wire, fiberglass, pvc pipes, and steel balls. I think that 2 uF at 18 kV could be enough to deform the cans.

i