BIG capacitor bank

vk2fro said:

Dare you to be the silly one to short that out with a screwdriver

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Sure, no problems ..... just let me find where i placed my asbesto armor, and the 5-meters-long plastic pliers for hold the screwdriver, and .....

HIML9: get one of those bomb defusing robots to take the screwdriver in - after all when you short it, it probably will become a bomb

Somebody at the university here told me they had a pulsed CO2 laser that made 1 kJ pulses, that's 1kJ of light. The cap bank they had was probably a bit smaller than the one HIMNL9 posted, but not much. I've seen the same large square blue caps as in the picture at my university. I can't remember if it was 1 millifarad at 10kV of at 30kV. That was long ago, way before my time

This is a BIG capacitor bank? Or not? I'm confused :thinking:

The English confuses me

Bluefan said:

Somebody at the university here told me they had a pulsed CO2 laser that made 1 kJ pulses, that's 1kJ of light. The cap bank they had was probably a bit smaller than the one HIMNL9 posted, but not much. I've seen the same large square blue caps as in the picture at my university. I can't remember if it was 1 millifarad at 10kV of at 30kV. That was long ago, way before my time

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The capacitor banks posted by HIMNL9 is a 9-megajoule (MJ) each bank (if I remember correctly).

I think this ones, are rather larger.

And is made for the Navy Rail Gun, (Naval Research, Arlington, VA)

This system will launch guided projectiles at speeds up to Mach 7.5 with a range of more than 200 nautical miles.

So far I just see a dude stealing cash from a vault to buy the caps for his cap bank

...and $1 bills no less. That armful of money would only get him a couple nice caps.

-Trevor

vk2fro said:

NOOOOOOO!!!!! what happened to that wonderful array of caps?! all 13.5kJ of them!

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I happened.

And why are they not wired up in series parallel for 700 volts, and wheres your charging system.

What do you plan to do with that bunch of caps?

In fact if you want to charge those off a 12 volt battery, I've designed a PCB for an efficient cap charger (see first post) with automatic shutoff once target voltage is reached. The circuit is from a member off 4hv.org, with a couple of revisions of my own (two different charge settings, metered output etc).

I've got 10 copies coming and 10 IRF540 mosfets, so if you'd like a cap charger (and can weild a soldering iron and use a multimeter), I'd be happy to send you a board and 2 mosfets to get you started (it will cost peanuts to mail). You just need to supply the common components (basically 8 fast diodes, 2 sand resistors, a bunch of 1/4 watt resistors and a few caps, a comparator and a voltage reference IC).

You will need to be handy with a multimeter, an o'scope would help but not essential, and 2 variable power supplies (you can get away with a fixed 12V 10A and a variable, or just a car battery and a variable psu).

Hardest part is winding the transformer. Which as far as transformers go, its pretty easy. 14 turns centre tapped on the primary and 200-400 turns on the secondary.

Once condition - you need to show us a video of your cap bank doing something (e.g. blowing up a wire, launching a hdd platter etc)

I will of course include instructions for assembly.

Cheers
Ben

edit: for those who are wondering WTF is a sand resistor:


I call them sand resistors, as it looks like they stole sand from the whitsunday islands to make the resistor body They are in fact, just a bigger cousin of a 2 watt resistor (which are the very fat "regular" looking resistors.)

edit2: Woohoo! my favourite line - 488nm - 488 posts

^ Shame ! ..... they are ceramic resistors, not sand resistors !

(and "The Sandman" can visit you, if you continue to call them "sand" resistors, you know ? ..... )

HIMNL9 said:

^ Shame ! ..... they are ceramic resistors, not sand resistors !

(and "The Sandman" can visit you, if you continue to call them "sand" resistors, you know ? ..... )

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ok - so you call sand resistors ceramic resistors - ok

I still need to build the busbar system and charger. I planned on designing my own flyback mode charger, since uzzor's boost converter would charge the bank a little too slow for my taste.

yeah - uzzors boost would be a bit slow for my bank once its finished with 40 caps. Thats why I took his 50 w capacitor charger and modified it.

Well seems like all my metal is gone. :-(

I have about 80lbs of lead left over from an x-ray experiment, maybe I can take that to the scrapyard to get some copper pipe.

Well the stockyard won't sell me any aluminum or copper because "people can make bombs with it." I fear for the future of this country...

..but now I have 90 capacitors and no way to connect them

grenadier said:

Well the stockyard won't sell me any aluminum or copper because "people can make bombs with it." I fear for the future of this country...

..but now I have 90 capacitors and no way to connect them

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Will sufficiently hefty wire work? :s

-Trevor

hardware store - buy some copper tubing and hammer it flat (or wont they sell it to you). Yes its a PITA, but its an easy way to get a busbar.

Trevor: its easier to work with busbar - you simply drill it at evenly spaced intervals with a suitable drill bit - those of which happen to be the spacing between one caps terminal and the next, and the diameter of the hole in the connectors on top of the cap