Electromagnets

Meaningful discussion outside of the potato gun realm. Projects, theories, current events. Non-productive discussion will be locked.
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ShowNoMercy
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Fri Jun 08, 2007 7:30 am

How much amps are these caps putting out anyway? Cause the amperage needed to kill you is somewhere lower than one, so I think your safe.
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Hotwired
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Fri Jun 08, 2007 7:56 am

It depends on the resistance. The amps drawn and the capacitance determines how long the capacitor can keep it up for.

Slap a bit of copper across a 330v flash capacitor and you'll get a fair few hundred amps dashing across it for a smidegon of a second.
TurboSuper
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Fri Jun 08, 2007 8:43 am

It takes ~50mA across your heart for it to start fribrillating. You're usually in pretty good shape because dry skin is in the hundreds thousands of ohms. You'd need a pretty good bolt to kill you from a coilgun, those camera flashes just hurt like hell.
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VH_man
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Fri Jun 08, 2007 12:11 pm

hmmm. a camera flash would make a good prank......... sit down.... ZAP!

(confused person) WHAT THE F*** WAS THAT!
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joannaardway
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Fri Jun 08, 2007 12:55 pm

Hotwired wrote:It depends on the resistance. The amps drawn and the capacitance determines how long the capacitor can keep it up for.

Slap a bit of copper across a 330v flash capacitor and you'll get a fair few hundred amps dashing across it for a smidegon of a second.
I've been told it's probably closer to 5kA to 10 kA.

@Turbosuper: I think only ~5mA is well within the dangerous range, but currents lower that can be dangerous

300V (likelish voltage) / 500,000 ohms (very dry skin) = 0.6 mA (nasty sizzle, but not too dangerous)
300V / 1,000 ohms (rather wet skin) = 300 mA. (Cooked)

Don't handle caps with anything but perfectly dry skin. Even a slight amount of sweat on your hands could be fatal to you.
0.6 mA might not seem very high, but consider that mains shocks are lethal at less voltage than that on occassion, so:
DON'T F*** ABOUT WITH THEM, GOT IT?

A bit off topic, but I have the strange tendency of having an exceptionally high skin resistance (seems to be either genetic or diet, because I share it with my brother), which actually makes my skin resistance exceptionally high - as much as 10 times what some other people have. Great for coilgunning.

I also have very high natural body voltage (sometimes peaking over 1 volt between my hands). On some days, certain LED types will light when I hold one between my hands - wonderful party trick.
Novacastrian: How about use whatever the heck you can get your hands on?
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TurboSuper
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Fri Jun 08, 2007 4:27 pm

@Turbosuper: I think only ~5mA is well within the dangerous range, but currents lower that can be dangerous
Not so much...

http://www.osha.gov/SLTC/etools/constru ... rrent.html

...also, since it's a capacitor, it wont get you "stuck" to it. Still- wear gloves and be careful.
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Solar
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Sun Jun 10, 2007 12:44 am

You could use the solenoid in a piston config instead of a displacement config. You would only need to overcome the force briefly if you were pusing INTO the pressure volume chamber. Not sure what kind of current you would need per psi though. Try making a piston solenoid and measuring it's force fom r a 12, 24, 36 and 48 volt source.
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