What can I do with 64uF @ 4kV?
SpaceWyzard, Tue May 30 2017, 12:22AMI came across 8 8uF 4000v capacitors. The package looks similar to a microwave oven capacitor but about 3 times as large physically. I'm not sure what they came out of. Assuming I hooked them all together in parallel, is this enough to do any cool hv capacitor bank stuff like coin shrinking or can crushing? If not, what could I do with them? I hate to just let them sit there on the shelf.
Re: What can I do with 64uF @ 4kV?
klugesmith, Tue May 30 2017, 12:56AM
With those numbers, you can make a respectable can-crusher.
Depending on the capacitors' current rating, which depends on internal construction details, it could be a long or short-lived can crusher. Got any pictures to share with us? Are they by any chance defibrillator caps?
It's not necessarily optimum to connect them all in parallel. The potential can-crushing performance would be about the same if you run them all in series, or in a series-parallel combination (what RC model enthusiasts might call 2S4P, or 4S2P). Those configurations all have different requirements for charging supplies, discharge switches, resistors for voltage balancing, bleed resistors for safety, and optimal work coils. Crushing efficiency, and electrical stress on the individual capacitors, will be about the same for all those configurations.
All in parallel could be a good choice for general safety and ease of construction. You might find it likes 3 or 4 or 5 turn work coils. Bank configurations with lower capacitance and higher voltage would, in my unpracticed opinion, work best with coils that have more turns in about the same proportion.
klugesmith, Tue May 30 2017, 12:56AM
With those numbers, you can make a respectable can-crusher.
Depending on the capacitors' current rating, which depends on internal construction details, it could be a long or short-lived can crusher. Got any pictures to share with us? Are they by any chance defibrillator caps?
It's not necessarily optimum to connect them all in parallel. The potential can-crushing performance would be about the same if you run them all in series, or in a series-parallel combination (what RC model enthusiasts might call 2S4P, or 4S2P). Those configurations all have different requirements for charging supplies, discharge switches, resistors for voltage balancing, bleed resistors for safety, and optimal work coils. Crushing efficiency, and electrical stress on the individual capacitors, will be about the same for all those configurations.
All in parallel could be a good choice for general safety and ease of construction. You might find it likes 3 or 4 or 5 turn work coils. Bank configurations with lower capacitance and higher voltage would, in my unpracticed opinion, work best with coils that have more turns in about the same proportion.
Re: What can I do with 64uF @ 4kV?
SpaceWyzard, Tue May 30 2017, 01:02AM
Thanks for the quick reply! I don't have any pics at the moment but I'll post some tomorrow after work. Glad to know I'll be able to use these for something!
SpaceWyzard, Tue May 30 2017, 01:02AM
Thanks for the quick reply! I don't have any pics at the moment but I'll post some tomorrow after work. Glad to know I'll be able to use these for something!
Re: What can I do with 64uF @ 4kV?
teravolt, Tue May 30 2017, 01:35AM
you could also make a ring launcher charge it with a microwave oven transformer
teravolt, Tue May 30 2017, 01:35AM
you could also make a ring launcher charge it with a microwave oven transformer
Re: What can I do with 64uF @ 4kV?
SpaceWyzard, Tue May 30 2017, 02:12PM
So this is not my pic but I found one on ebay just like the ones I have. It is priced on ebay at 75$! And I got 8 of them for free! I had no idea they were so pricey!
Anyway, do you think these would hold up under pulse-rated activities? Or are they gonna die after a few shots?
SpaceWyzard, Tue May 30 2017, 02:12PM
So this is not my pic but I found one on ebay just like the ones I have. It is priced on ebay at 75$! And I got 8 of them for free! I had no idea they were so pricey!
Anyway, do you think these would hold up under pulse-rated activities? Or are they gonna die after a few shots?
Re: What can I do with 64uF @ 4kV?
hen918, Tue May 30 2017, 03:11PM
careful, the case is one of the terminals. looks like parallel is definitely best
hen918, Tue May 30 2017, 03:11PM
careful, the case is one of the terminals. looks like parallel is definitely best
Re: What can I do with 64uF @ 4kV?
klugesmith, Tue May 30 2017, 07:31PM
Another warning. Those capacitors, and things you make with them, can deliver lethal electric shocks. As dangerous toys, they are in a league with microwave oven transformers. Maybe more dangerous, because (among other things) ...
1) high voltage can persist long after the apparatus is turned off or unplugged.
2) MOT's have intrinsic current limiting. HV capacitors don't.
I hope that when we see pictures of your windfall, the shorting wires or bleed resistors will be visible.
You might also want to look up dielectric absorption in capacitors. After a rapid discharge from HV to zero volts, if the load is disconnected right away the voltage will creep back up. A minute later, it could be enough for a painful and surprising shock, with consequential personal injury or property damage. The effect is not a problem with MO capacitors, because they have built-in bleeder resistors.
klugesmith, Tue May 30 2017, 07:31PM
Another warning. Those capacitors, and things you make with them, can deliver lethal electric shocks. As dangerous toys, they are in a league with microwave oven transformers. Maybe more dangerous, because (among other things) ...
1) high voltage can persist long after the apparatus is turned off or unplugged.
2) MOT's have intrinsic current limiting. HV capacitors don't.
I hope that when we see pictures of your windfall, the shorting wires or bleed resistors will be visible.
You might also want to look up dielectric absorption in capacitors. After a rapid discharge from HV to zero volts, if the load is disconnected right away the voltage will creep back up. A minute later, it could be enough for a painful and surprising shock, with consequential personal injury or property damage. The effect is not a problem with MO capacitors, because they have built-in bleeder resistors.
Re: What can I do with 64uF @ 4kV?
SpaceWyzard, Tue May 30 2017, 09:35PM
Got it. Definitely use bleeder resistors. I like living and all my digits so no problem there.
SpaceWyzard, Tue May 30 2017, 09:35PM
Got it. Definitely use bleeder resistors. I like living and all my digits so no problem there.
Re: What can I do with 64uF @ 4kV?
radiotech, Fri Jun 02 2017, 02:53AM
Will 64 joules flash a Xenon lamp sufficiently to excite a ruby rod into lasing ?
radiotech, Fri Jun 02 2017, 02:53AM
Will 64 joules flash a Xenon lamp sufficiently to excite a ruby rod into lasing ?
Re: What can I do with 64uF @ 4kV?
Dr. Slack, Fri Jun 02 2017, 06:53AM
Even though case is one terminal, you need not connect them all in parallel. A bipolar 4P2S configuration with all cases grounded would let you double the voltage and still have no more than 4kV to ground. However, the +4/-4kV terminals may complicate the switching/charging/loading. Happy can crushing!
BTW, there's more than one way to crush a can. As well as the obvious 'turns round the middle', there's also the pancake ring-launcher stylee. I made a spiral pancake coil of IIRC 8 turns of insulated 4mm wire which conformed closely to the bottom of the can. This launched the bottom of the can through the top, and smashed the whole thing into the ceiling.
Dr. Slack, Fri Jun 02 2017, 06:53AM
Even though case is one terminal, you need not connect them all in parallel. A bipolar 4P2S configuration with all cases grounded would let you double the voltage and still have no more than 4kV to ground. However, the +4/-4kV terminals may complicate the switching/charging/loading. Happy can crushing!
BTW, there's more than one way to crush a can. As well as the obvious 'turns round the middle', there's also the pancake ring-launcher stylee. I made a spiral pancake coil of IIRC 8 turns of insulated 4mm wire which conformed closely to the bottom of the can. This launched the bottom of the can through the top, and smashed the whole thing into the ceiling.
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