Exploding cap

the_random_hero · September 27, 2007, 12:26:57 AM

Next time we get let loose in the labs, I'll take a video of us exploding some caps. We found that half of them detonated out the top (as they are designed to do), while the other half just blew their asses out. We tried everything from 'super' caps (off motherboards), low ESR caps and just the general sort of electrolytics. The normal sort seemed to do a bit more damage

The thing with exploding LED's is that you're likely to get a nice shard of glass/plastic flying towards you at a fair amount of speed. I sure wouldn't like a piece of that hitting me in the eye

MKB · September 27, 2007, 07:59:59 AM

That is quite a mess on that board, it also took a chunk out of the op amp. Must have made quite a bang.

Tantalums have the nasty habit of catching on fire, like this: http://www.youtube.com/watch?v=wWIEVOyNoEA We don't like using them in power supplies for that reason. It also seems the ones with voltages over 25v or so are more likely to go boom.

Paul Perry (Frostwave) · September 28, 2007, 05:09:24 AM

Does anyone else find it ironic that a thread on "exploding caps" should be started by someone called "wounded paw"?

Though maybe 'Odin" would be even more apt...

Wounded Paw · September 28, 2007, 01:10:34 PM

exploding cap ... wounded paw

Anyways, fixed it. Replaced the cap, the TL072 IC and the 78L05 voltage regulator and it works like new.

sshrugg · September 28, 2007, 02:54:30 PM

Quote from: Wounded Paw on September 28, 2007, 01:10:34 PM
Anyways, fixed it. Replaced the cap, the TL072 IC and the 78L05 voltage regulator and it works like new.

Dude! Great news!

runmikeyrun · September 29, 2007, 11:43:43 AM

haha, that video reminded me of my high school electricity class, we blew up caps like that too only we had smaller ones that didn't make as big of a bang. Another fun thing to do with those electricity experimenter kits: sharpen both ends of a pencil, clip one of each lead on each side, and slowly increase the voltage until the wood burns off, the graphite glows, and eventually turns white like a light bulb filament and then breaks.

we also thought it was funny when we rigged up one guy's metal/masonite stool w/ 115v AC so when he sat down his arse got blasted

sshrugg · September 29, 2007, 01:21:19 PM

Quote from: runmikeyrun on September 29, 2007, 11:43:43 AM
we also thought it was funny when we rigged up one guy's metal/masonite stool w/ 115v AC so when he sat down his arse got blasted

That could have been bad.

nebucanazza · September 30, 2007, 01:58:50 AM

Holy shit!! I never knew caps exploded so violently. Reminds me of the time when we vaporized some 5A fuse wires in my electro-mechanical machines lab during college. One of the guys in my group actually shorted each of the 3 phases of 230V AC mains onto itself

Needless to say, when the blade switch was thrown there was a flash and a loud bang! We punished that guy by making him throw the switch every time while we stood our distance

darron · September 30, 2007, 01:10:30 PM

another good one for class is to get a massive capacitor and charge it to full voltage, then disconnect it and short it with an insulated screwdrive. BANG! of course... seems safer than connecting three phases (415V here).

nebucanazza · September 30, 2007, 01:39:41 PM

Oh definitely...we were lucky not to trip the power supply of the whole lab. Of course it was not done on purpose.

I guess what you are describing might easily happen inside an amp. Imagine if any of the caps inside carrying 400V+ get shorted somehow

darron · September 30, 2007, 01:41:58 PM

hopefully not by fingers or two different hands

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Exploding cap