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Nicko

Sat Aug 08 2009, 10:16AM

Registered Member #1334 Joined: Tue Feb 19 2008, 04:37PM
Location: Nr. London, UK
Posts: 615

I have a bunch of these - banks of 500V 2200uF RIFA PEH 169-series caps... Fully populated there are 12 in a bank, i.e. 3300 J per bank, and there are a lot of them... (not counted)

I'm thinking washer-launcher, can crusher, .... any other ideas?

Something made from these will be at Cambridge...

Proud Mary

Sat Aug 08 2009, 11:54AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Dare to be different, and use them to investigate a phenomenon still little understood.

Have a read of this, Nick:

Underwater Spark Sources: Some experimental information.
Report Reference: 440R0102 by J. R. Nedwell, internal company document.

Which you can download for free here:

I'm extremely interested in this myself, since in combination with sonoluminescence, is thought by some authors to produce braking radiation.

From personal experience, I suggest doing the experiment in a domestic hot water tank, a cattle trough, or old bath tub at the end of a long control wire well away from anything or anyone that might be harmed.

Connect your capacitors in series till they can safely hold off 20kV, and then charge them up to half that voltage at the very most.

Make sure there are no dogs around whose hearing might be harmed by the underwater detonation. Warn neighbours. Start at the small end.

A 1000uF capacitor charged to 10kV will store 50E3 Joules, which might well disintegrate a riveted cattle trough or hot water tank.

You'll find a lot of recent academic papers online if you Google "underwater spark discharge" and "underwater electrical discharge."
It's something people are still researching, so you'll be very cutting edge with this kind of experiment. You might want to synchronize your control cable with a camera and a video so as not to miss the event. Wear laser proof safety glasses or welding goggles and ear defenders even at a distance.

Is it Father Nick or Old Nick I wonder?

The means of permanently damaging your hearing are now in your own hands, Nicko. Take care, record what you do, and have fun!

Hazmatt_(The Underdog)

Sat Aug 08 2009, 11:04PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

The kids really like my Washer tosser, but its only 160J of bang energy, for safety. I get about 14 feet at full capacity with my Al washer. A Mg washer would probably fly to the Moon.. heheheh.

I demonstrate the solid ring and a split ring. Interestingly enough, the split ring still moves with 160J.

Arcstarter

Sun Aug 09 2009, 12:32AM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

Wow, those things are awesome!

Well, i like washer launchers. With 624 joules with crappy capacitors, with a very slow discharge, was enough to break a HDD in half if a pipe was held above it. It would dent the disk purely from acceleration, and if i put a can on top with a piece of wood on top, it would shrink it to about 4cm, and if i put something on it that would not move, maybe 2-3cm.

With those much higher quality capacitors and alot less inductance (mine where 5 bucks) and more power, i can't even imagine what they would do.

Though, mine was at 800 volts, and faster rise time is needed. I used no anti reverse diodes.

Nicko

Sun Aug 09 2009, 03:42AM

Registered Member #1334 Joined: Tue Feb 19 2008, 04:37PM
Location: Nr. London, UK
Posts: 615

Harry wrote ...

Dare to be different, and use them to investigate a phenomenon still little understood.

Have a read of this, Nick:

Underwater Spark Sources: Some experimental information.
Report Reference: 440R0102 by J. R. Nedwell, internal company document.
...

That was a really interesting read - quite simple to do - not sure I'll get something like that ready in a short time (too many projects) but definitely something for the winter months. We have a family farm which means I can get safely away from the general populace by maybe 1/2 mile for any big bangs... oh, and cattle troughs a-plenty...

You talk about high energy values - the paper discusses only up to 10J (actually 0.1uF @ 10Kv which is 5J). At the moment, I don't have anything that big. I have a bunch of Maxwell caps, but they are only 0.03uF (at 35KV), however 5 MOCs in series might do the trick (not discharge caps, but might work).

wrote ...

Is it Father Nick or Old Nick I wonder?

The means of permanently damaging your hearing are now in your own hands, Nicko. Take care, record what you do, and have fun!

I am a father, and, no thank you very much, I'm not that old. But old enough to respect what I'm up against

Cheers

aonomus

Sun Aug 09 2009, 04:40PM

Registered Member #1497 Joined: Thu May 22 2008, 05:24AM
Location: Toronto, Ontario, Canada
Posts: 801

Try to do series/parallel strings to get a higher voltage so you get faster current rise. It enables so much more (can crushing perhaps, and just plain exploding stuff).

You might want to consider doing some railgun experiments with that many around since you have the space of a farm to fire it off.

Arcstarter

Sun Aug 09 2009, 08:36PM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

aonomus wrote ...

Try to do series/parallel strings to get a higher voltage so you get faster current rise. It enables so much more (can crushing perhaps, and just plain exploding stuff).

You might want to consider doing some railgun experiments with that many around since you have the space of a farm to fire it off.

Yup. That is what i was getting at. It makes a huge difference. Though the same overall energy storage, it made my bank many *times* greater. They are crappy, but putting them in series helped a lot.

Proud Mary

Mon Aug 10 2009, 12:45AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Ha, ha Nick, I thought the photograph was of you - hence I thought 'Father Nick' - someone shortly to be defrocked! Now I guess it may be a picture of a television character, which is why I wouldn't have recognized it.

It's true that Dr Nedwell talks only of rather parsimonious discharges of 10J, but if there is any hope of detecting Bremsstrahlung with a detector array placed around the tank, I'd put my money on the 50E3J, because the detectors will be destroyed in the first few microseconds. (Â£Â£Â£)

Were you to attempt these experiments, I would strongly advise you to use thermionic technology, which is vastly simpler for the amateur to harden against violent EMP-like transients than anything solid state that is relatively easy to make. (In the former USSR, a wonderful range of exquisitely miniature valves was produced and used in HEMP hardened circuitry, long after it was made public that DoD contractors had been using consumer-grade ICs bought in Radio Shack in the Minuteman Missile Guidance Set!) These splendid Soviet miniature valves are now as cheap as chips in Russia, and have flying leads, rather than pins, so are pleasant to work with on the small scale if size is an issue for you, as it is with many insecure men.

I myself have about half a Euro pallet of new large can high voltage aluminium electroytics, so could relatively easily bolt some of them into bin racks with copper plumbing pipe bus bars. They are mostly inverter grade caps, but I would still expect them to survive half a dozen shots or so, if conservatively rated.

A series string of 25*15000uF/450V ~ 555uF/>10kV

If this capacitor set was conservatively charged to 5kV, half the nominal vmax (wkg) we should have about 7E3J, not quite the Manhattan Project, but 7E2 larger than Dr Nedwell's test model.

The wave front geometry is critical to the truly spectacular, so this I would achieve by putting in parallel with the electroytics, a much smaller value of ultra-low inductance long parallel plate capacitors I have copied from a Russian design, which would extend for two metres on either side of the spark gap like wings.

The initialization streamer would be fired off by a small hydrogen thyratron located in the tank immediately below the spark gap. The ultrafast capacitors will then open the discharge with a steep wavefront, with the electrolytics following on some nanoseconds behind.

An acoustics person might be able to contribute some reflectors so the shock wave is propelled back into the centre precisely at the right instant to create standing waves which would add to eachother to produce a substantial cavitation vacuum (sic) through which the discharge would now pass, hopefully producing a big enough blast of braking radiation to be detected by the detector array arranged around the tank in ports.

My approach to this kind of experiment would be to put together a little team which could include a mathematician, a generalist physicist, a competent constructor who can more or less build things to order, a wireman or woman much better than myself, and some general helpers prepared happily to turn their hand to whatever needs doing.

I'd put this kind of endeavour in the same class as high altitude amateur rocketry, where the work to be done far exceeds the ability of a single individual, and has the same social enjoyment of working in a dedicated team.

Why waste your time with parlour tricks like shrinking coins when you could put the same amount of effort into the world of real experiment, where there is at least the possibility of discovering something wholly new.

As you'll see from Google there are university teams doing similar experiments right now, and it's extremely unusual for a wholly new field to be accessible to the amateur without a great lab and facilities behind him or her. Of course, the scenario I have painted in the grand manner would be preceeded by much smaller experiments of the kind outlined by Dr Nedwell, but a man with set-aside is a man able to get involved in the larger tests without too much difficulty.

Nicko

Mon Aug 10 2009, 06:25AM

Registered Member #1334 Joined: Tue Feb 19 2008, 04:37PM
Location: Nr. London, UK
Posts: 615

Harry wrote ...

Ha, ha Nick, I thought the photograph was of you - hence I thought 'Father Nick' - someone shortly to be defrocked! Now I guess it may be a picture of a television character, which is why I wouldn't have recognized it.

Its a picture of Father Jack Hackett. He's my role model

In "reality" he's a character from the cult show "Father Ted" - Jack, is lethal but has the constitution of a Ox. Played by Frank Kelly (a very good Shakespearean actor!), who is apparently not very well at the moment - we wish him well...

See

for more info on the characters.

see

for an example of Jack in action...

Proud Mary

Mon Aug 10 2009, 06:34AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Ah yes, so it is, Nick - I've seen the show once or twice at the house of a friend who has a tele.

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