Why not keep them and start trying to shink coins?
http://205.243.100.155/frames/shrinkergallery.html

This site has been recently edited to take out most of the technical
details. I suspect it was a bit too dangerous for the average user.

Ignoramus27088 wrote:
Got myself some capacitors for $10 apiece.

http://cgi.ebay.com/ws/eBayISAPI.dll...tem=7603382621

The specs are 22 kV, 1 uF, discharge capacitor. See

http://igor.chudov.com/tmp/cap.jpg

The seller was wrong in describing them as 22 VOLT capacitors. They
are 22 KILO volt capacitors. (the seller is Fermilab).

They are similar to this one:

http://cgi.ebay.com/ws/eBayISAPI.dll...tem=7598631638

but have twice more capacitance.

Anyway, here is my question. I have a 9 kV DC power supply. (a
Franceformer). How can I safely test these caps before selling
them. At 22 kV, they can store about as much energy as a .22 bullet,
according to my calculations.

It would be less at 9 kV, but still, obviously, very deadly.

So. What is a safe way to charge them, verify that they hold the
charge, and then DIScharge them at 9 kV.

i

On Fri, 31 Mar 2006 23:40:29 GMT, RoyJ wrote:
Why not keep them and start trying to shink coins?
http://205.243.100.155/frames/shrinkergallery.html

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

This site has been recently edited to take out most of the technical
details. I suspect it was a bit too dangerous for the average user.

The Wayback Machine (www.archive.org) will have the old version of the
site, of course.

On 1 Apr 2006 15:55:49 GMT, Dave Hinz wrote:
On Fri, 31 Mar 2006 23:40:29 GMT, RoyJ wrote:
Why not keep them and start trying to shink coins?
http://205.243.100.155/frames/shrinkergallery.html

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

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

In rec.crafts.metalworking Ignoramus26172 wrote:
On 1 Apr 2006 15:55:49 GMT, Dave Hinz wrote:
On Fri, 31 Mar 2006 23:40:29 GMT, RoyJ wrote:
Why not keep them and start trying to shink coins?
http://205.243.100.155/frames/shrinkergallery.html

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

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 used to crush quarters. "copper gas" is the least of the problem you
will encounter, and not the reason the solenoids explode.

20 kV is low for quarter crushing.

If it matters, I used 14uF of 50kV energy discharge caps. 30-35kV worked
the best, although inductance is of the circuit is as important as the
voltage.

I didn't dare to connect a scope up to measure the waveforms.

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.

Use pipe not wire for can crushing.

On Sat, 1 Apr 2006 23:31:45 +0000 (UTC), Cydrome Leader wrote:
In rec.crafts.metalworking Ignoramus26172 wrote:
On 1 Apr 2006 15:55:49 GMT, Dave Hinz wrote:
On Fri, 31 Mar 2006 23:40:29 GMT, RoyJ wrote:
Why not keep them and start trying to shink coins?
http://205.243.100.155/frames/shrinkergallery.html

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

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 used to crush quarters. "copper gas" is the least of the problem you
will encounter, and not the reason the solenoids explode.

20 kV is low for quarter crushing.

If it matters, I used 14uF of 50kV energy discharge caps. 30-35kV worked
the best, although inductance is of the circuit is as important as the
voltage.

I didn't dare to connect a scope up to measure the waveforms.

That means I do not have enough capacitors.

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.

Use pipe not wire for can crushing.

Thanks... So, what would you say, would 1 uF at 22kV crush a can?

i

Ignoramus26172 wrote:
On Sat, 1 Apr 2006 23:31:45 +0000 (UTC), Cydrome Leader wrote:

In rec.crafts.metalworking Ignoramus26172 wrote:

On 1 Apr 2006 15:55:49 GMT, Dave Hinz wrote:

On Fri, 31 Mar 2006 23:40:29 GMT, RoyJ wrote:

Why not keep them and start trying to shink coins?
http://205.243.100.155/frames/shrinkergallery.html

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

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 used to crush quarters. "copper gas" is the least of the problem you
will encounter, and not the reason the solenoids explode.

20 kV is low for quarter crushing.

If it matters, I used 14uF of 50kV energy discharge caps. 30-35kV worked
the best, although inductance is of the circuit is as important as the
voltage.

I didn't dare to connect a scope up to measure the waveforms.


That means I do not have enough capacitors.


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.

Use pipe not wire for can crushing.


Thanks... So, what would you say, would 1 uF at 22kV crush a can?

i


Nice catch!

For can crushing you need a minimum of about 400 Joules, and for coin
crushing at least 2000 Joules. I happen to use a bank rated at 140 uF at
12 kV. I also use Maxwell energy discharge caps, but mine are Series C
100 kA high current type. Because mine are rated for only 20% voltage
reversal, I only take the bank up to about 9500 volts (6300 Joules) for
coin crushing. For can crushing, I only go to about 3500 Joules (mainly
to reduce wear and tear on the spark gap switch).

Using all of your 15 caps in parallel would give you a capacitor bank
capable of delivering ~3 kJ, so you are in the right ballpark. However,
can crushing (especially) and coin crushing can cause highly oscillatory
discharges. Rapid voltage reversals are very stressful on a HV
capacitor's dielectric system, and most of Maxwell's pulse caps are only
rated for 10-20% voltage reversal (at faceplate voltage), so you don't
want to run these caps anywhere near their full faceplate voltage if you
are doing can or coin crushing - they WILL prematurely fail. And, you
definitely don't want to be anywhere near the caps when the energy from
the other 14 capacitors dump everything they've got into a single
faulting cap... :^)

Looking at the "Frankenstein" insulator style used on your caps, they
are likely not rated for more than 2 - 5 kA peak (the folks at General
Atomics can probably provide you with their actual specs):
http://www.gaep.com/capacitors.html).

Running more caps in parallel will help to share the peak current seen
by each capacitor. If you plan to do any coin shrinking, treat the coil
like a small bomb, with copper shrapnel being ejected at hyper velocities.

There's more information on my site:
http://205.243.100.155/photos/shrinker5.pdf (1 page summary)
http://205.243.100.155/frames/shrinker.html (more gory details)

And, always remember to be afraid - very afraid - of the energy stored
in these caps. They will not give you any second chances. =:^[

Bert
--
-------------------------------------------------------
We specialize in UNIQUE items! Coins shrunk by huge
magnetic fields, our "Captured Lightning" Lichtenberg
Figure sculptures, and Out-of-Print technical Books.
Visit Stoneridge Engineering: http://www.teslamania.com
-------------------------------------------------------

In rec.crafts.metalworking Ignoramus26172 wrote:
On Sat, 1 Apr 2006 23:31:45 +0000 (UTC), Cydrome Leader wrote:
In rec.crafts.metalworking Ignoramus26172 wrote:
On 1 Apr 2006 15:55:49 GMT, Dave Hinz wrote:
On Fri, 31 Mar 2006 23:40:29 GMT, RoyJ wrote:
Why not keep them and start trying to shink coins?
http://205.243.100.155/frames/shrinkergallery.html

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

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 used to crush quarters. "copper gas" is the least of the problem you
will encounter, and not the reason the solenoids explode.

20 kV is low for quarter crushing.

If it matters, I used 14uF of 50kV energy discharge caps. 30-35kV worked
the best, although inductance is of the circuit is as important as the
voltage.

I didn't dare to connect a scope up to measure the waveforms.

That means I do not have enough capacitors.

I never said it wasn't enough. This is what experimenting is for.


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.

Use pipe not wire for can crushing.

Thanks... So, what would you say, would 1 uF at 22kV crush a can?

Probably. Can crushing is actually pretty boring though. I crushed more cans just
putting them in the coil form than from actually using it. Cans are so weak, it's
just not interesting.

I might try again with full cans of pop. That would be messy, but more pleasing
to watch, and a bit harder to pull off.

On 1 Apr 2006 15:55:49 GMT, Dave Hinz wrote:
On Fri, 31 Mar 2006 23:40:29 GMT, RoyJ wrote:

Why not keep them and start trying to shink coins?
http://205.243.100.155/frames/shrinkergallery.html

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

This site has been recently edited to take out most of the technical
details. I suspect it was a bit too dangerous for the average user.

Well of course it is! That's what makes it fun... And as I recall
he had huge warning signs plastered all over the site, too. And
triggered the shrink blast from outside the garage while standing
behind a healthy barricade like a truck.

That's why I tell all my customers the old saw that is SO true:
"I'm a trained professional - If you see me running, try to keep up."

The Wayback Machine (www.archive.org) will have the old version of the
site, of course.

But usually minus all the pictures.

-- Bruce --

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
Spamtrapped address: Remove the python and the invalid, and use a net.

Bruce,

I like the saying that there are no old, bold captains.

i