LOL - Exploded cap.

I have a circuit that powers a 11watt fluro tube from 12v, so i decided to have some fun and ramped it up to 16v, 20v, kept turning to max out this step up voltage regulator and i was starting to hit around 25volts and BANG!!!!, the input capacitor exploded the whole house heard it, it was a 16v 10uf or pf, not sure, i replaced it with a 100pf 25v cap and cranked up the voltage to 22 volts getting a spark gap of around 6cm :D but anyway whatever happened it knocked out my computer (not even on the same circuit) reset my arduino (Which shared the same battery) something weird happened just before or just after huge amounts of energy for a brief moment was consumed my voltage regulator could not care less it seems must have spiked over 6amps which it was happy with, shame the voltage regulator powering the arduino could say the same, and as for why my computer died (power on, screen off) usb is not connected there's no shared link, it's isolated, but it was enough to make the arduino go spastic and tell me there's a power out (located about 1 meter away).

as for the bang, it's deafening not nice .... but sure was FUN!!!!

cjdelphi: as for the bang, it's deafening not nice .... but sure was FUN!!!!

Yeah, those things are noisy when they go off.

Exploding caps can easily take out an eye or two.

What some of us used to do in college was to get some little 1 or 10uF electrolytics, put them inside a pen casing with the legs hooked up in reverse to a bench supply at full voltage, and use them as cannons to fire diodes across the room. A bit childish to say the least... but nobody died :)

http://www.youtube.com/watch?v=9jDsNe_bmtE

3:40

so what happens to all the stored energy? dissipated by heat?

and as for why my computer died (power on, screen off) usb is not connected there's no shared link, it's isolated,

My guess is that the high-voltage arced back throught the power supply into your house-power, causing a power-line spike.

dhenry: Exploding caps can easily take out an eye or two.

I've got a couple of 68000uF caps on the shelf. They look at least 20 years old, maybe more. We used to hold a couple of wires on them to charge them up then melt nails across the screw terminals on the top. Stuff like that. Here's one of them with a couple of normal size components for comparison.

One day a little 10uF electrolytic exploded quite close to me. The metal case flew across the room fast enough to flatten itself against the opposite wall (which means it must have been going about the speed of a bullet...)

Ever since then I've been too scared to charge the big one.

cjdelphi: so what happens to all the stored energy? dissipated by heat?

Heat+light+sound. A bit like an electric firecracker.

fungus:

dhenry: Exploding caps can easily take out an eye or two.

I've got a couple of 68000uF caps on the shelf. They look at least 20 years old, maybe more. We used to hold a couple of wires on them to charge them up then melt nails across the screw terminals on the top. Stuff like that. Here's one of them with a couple of normal size components for comparison.

One day a little 10uF electrolytic exploded quite close to me. The metal case flew across the room fast enough to flatten itself against the opposite wall (which means it must have been going about the speed of a bullet...)

Ever since then I've been too scared to charge the big one.

Fun, but not as dangerous as back in the old days, when there were 500V plus power supplies on TV sets, and the "diodes" were vacuum tube rectifiers, which tended to croak a lot.

I once saw a rectifier short out, the plate glowed an intense red for a couple of seconds, then the large METAL-case electrolytic cap [roughly 5" tall and 1.5" in diameter] exploded, and the can flew up like a rocket and put a dent in the ceiling.

Ahaa, those good ol' pre-1960 murderboxes :D They definitely don't make 'em like they used to.

I’ve had a few electrolytics pop in my time with electronics. First I had a power supply with a shorted pass transistor (linear regulator) and hooked up an old car clock. After trying to get it to work (not thinking of an overvoltage problem) the electrolytic popped. Second incident was with a power inverter. Plugged it in and the cheap capacitor popped immediately. I was lucky that they were enclosed in a device at the time as the first one definitely would have gone flying.

cjdelphi: I have a circuit that powers a 11watt fluro tube from 12v, so i decided to have some fun and ramped it up to 16v, 20v, kept turning to max out this step up voltage regulator and i was starting to hit around 25volts and BANG!!!!, the input capacitor exploded the whole house heard it, it was a 16v 10uf or pf, not sure, i replaced it with a 100pf 25v cap and cranked up the voltage to 22 volts getting a spark gap of around 6cm :D but anyway whatever happened it knocked out my computer (not even on the same circuit) reset my arduino (Which shared the same battery) something weird happened just before or just after huge amounts of energy for a brief moment was consumed my voltage regulator could not care less it seems must have spiked over 6amps which it was happy with, shame the voltage regulator powering the arduino could say the same, and as for why my computer died (power on, screen off) usb is not connected there's no shared link, it's isolated, but it was enough to make the arduino go spastic and tell me there's a power out (located about 1 meter away).

as for the bang, it's deafening not nice .... but sure was FUN!!!!

In high school (1970's) I once "plugged" several large (1000 uF) electrolytic caps into the outlets in the school metal shop. They shut off the circuit breakers at the end of the day, so the caps sat there until the next morning.

Next morning when the instructor turned on the breakers, all the caps exploded in a shower of paper shreds and smoking electrolyte oil!

Nobody ever found out who did it.........

krupski,

I hope your teacher catches you now that you confessed. On the other side of the fence, a retired colleague of mine used to charge up a large capacitor, realizing some of his students has fallen asleep during lecture, then discharged it with a metal piece. The loud bang woke up everyone, very angry. That's how he got back at the sleepers. I bet he'd use a ruler to slap them if they still allowed that. Waste of money, I say, to sleep in a classroom.

liudr: krupski,

I hope your teacher catches you now that you confessed. On the other side of the fence, a retired colleague of mine used to charge up a large capacitor, realizing some of his students has fallen asleep during lecture, then discharged it with a metal piece. The loud bang woke up everyone, very angry. That's how he got back at the sleepers. I bet he'd use a ruler to slap them if they still allowed that. Waste of money, I say, to sleep in a classroom.

The priests just used to throw erasers at us. And we had to wear dark sports jackets to class...

Many years ago there was a trick played on Noob television technicians by the "Crew". The thing was to charge a 40uF cap to 200 - 400 V and carefully fold the wires (axial lead part) back to the capacitor body and then yell to the Noob "Here Catch" and toss the part at the noob. The practice came to an end one day when the guy that caught the "hot" one took the guy that made it and threw it outside and thrashed him severely. I'd have done the same If I had caught one... but I was aware of the practice... The sweeper filled me in first..

Bob

What's really fun is to charge a cap to like 200v, then "taze" unexpecting friends lmao

That's Exactly what was going on... the real difference was asking the person to "Taze" them selves by saying "Here, Catch". Still was a mean trick and potentiallly very dangerous as there is a Lot of energy in a 40uF cap charged to 250 - 300 VDC at least 2 orders of magnitude greater than the Tazer...

Bob

Lol I musta posted that just after you did, didn't see that, it is quite funny, and it is cool how much energy the cap can disharge at once, I used a large cap charged to 200v to help me "safely " blow out the filament of a car bulb that I was going to use for a sort of neon lamp but just without the neon