Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Exploding capacitor

  1. Dec 17, 2003 #1
    exploding capacitor :(

    I got my electronic lab today and start playing with the 470 uf capacitor. I connected to a 9v source and it exploded . The casing went across the room. what happened? The capacitor was an electrolytic capacitor. Can having the wrong polarity be the cause? :smile: If so, why?

    Also, i think I busted one of my LED on my kit by not checking the polarity.
     
  2. jcsd
  3. Dec 17, 2003 #2
    Re: exploding capacitor :(

    you bet
    welcome to the world of capacitor killers

    Well, the college days are long gone, but I think the explanation was that when he wrong polarity is applied, the capacitor acts as a resistor, heats, gas bubles are formed in the electrolite and thus results a "pretty" explosion.

    http://www.rubycon.co.jp/en/faq/alumi.html
     
    Last edited: Dec 17, 2003
  4. Dec 17, 2003 #3
    regarding transistors (3 prongs), does the Base require a resistor in series to prevent burn out? I think I shorted one out cuz it smells weird...
     
  5. Dec 17, 2003 #4
    Though, you can't blow up capacitor with 9V battery. So you must be using quite powerful supply. Hopefully DC not AC?
    Suggestion: DON'T take fist-sized electrolytic capacitor with low voltage rating and connect it directly into the mains.. It WON'T be pretty If you'll survive, it'll take weeks to cleanup.

    Transistors allow max 1V across its base to emitter. If there is no resistence in series, then it acted like a short circuit to the power. If you applied 9V powerful source to it directly, you are lucky that it didn't go ballistic.

    Man, I think you could use a helmet for a start :wink:
     
  6. Dec 17, 2003 #5
    ok then, so if a capacitor takes such low voltage does that mean we can jack up the amps, and really have fun? -- I have a helmet AND goggles
     
  7. Dec 17, 2003 #6
    I'm using dc 9v and yes it did exploded! It was like a firecracker. Luckly the casing didn't hit me in the face. I assume it is safe because the electronic project kit is made for 10 or older. Wtf. Maybe I should call the company and complain. Who says I was using a hand size capacitor? The one i was using was a 470uf so it was small.


    // Though, you can't blow up capacitor with 9V battery. So you must be using quite powerful supply. Hopefully DC not AC?
    Suggestion: DON'T take fist-sized electrolytic capacitor with low voltage rating and connect it directly into the mains.. It WON'T be pretty If you'll survive, it'll take weeks to cleanup.

    Transistors allow max 1V across its base to emitter. If there is no resistence in series, then it acted like a short circuit to the power. If you applied 9V powerful source to it directly, you are lucky that it didn't go ballistic.

    Man, I think you could use a helmet for a start //
     
  8. Mar 12, 2008 #7
    Do capacitors grow?

    Do capacitors grow before it explodes or does it just explode?
     
  9. Mar 13, 2008 #8
    Apart from the voltage applied if the capacitor is saturated, a shunt or short circuit will also do it.
     
  10. Mar 13, 2008 #9
    The effect of a connecting an electrolytic the wrong way across a power supply is usually fair instantaneous.
     
  11. Mar 13, 2008 #10

    berkeman

    User Avatar

    Staff: Mentor

    You guys are like bulls in a china shop! Geeze! Your TA must be a wreck.
     
  12. Mar 13, 2008 #11

    dlgoff

    User Avatar
    Science Advisor
    Gold Member

    :rofl::rofl::rofl: You never blow up a cap before berkeman?
     
  13. Mar 13, 2008 #12

    berkeman

    User Avatar

    Staff: Mentor

    Well, to be honest, yes. But never on purpose, and the couple times it's happened, it's scared the bejeezus out of me. Sounds like a gunshot going off :eek:

    When we do serious Surge testing of prototypes, the protos are under a protective plastic enclosure, and we are standing back and generally ready for the noises when something fails (MOVs are loud too).

    When I work with open assemblies that have electrolytic caps on them, and I'm doing any kind of circuit work that could cause a problem (like power supply work where the supply might go unstable and overvoltage), I always at least wear safety glasses, just in case one of the EL caps lights off. Oh, and I try not to have them pointed at me for any length of time....

    Be safe out there kids!
     
  14. Mar 13, 2008 #13
    I just blew one up at work yesterday. Scared the crap out of me. The cap was on the bottom side of the board and I was poking along the top side.
     
  15. Mar 14, 2008 #14

    Ouabache

    User Avatar
    Science Advisor
    Homework Helper

    Berkeman reminds me of some of my earlier experiments; I fired up a power supply circuit using some filter caps the size of a peanut butter jar. I needed that size capacitor, because it was for low frequency work. I had it set up in a copper shielded room and had just walked out, when BANG :surprised. There were few professors on my hall, who I am sure, not only woke them up, but gave them a chuckle :smile: All the white electrolyte spilled out too. What a mess to clean up.. So the moral is, double check your wiring to be sure you've got the correct polarity on your electrolytics.
     
    Last edited: Mar 14, 2008
  16. Mar 14, 2008 #15

    Ouabache

    User Avatar
    Science Advisor
    Homework Helper

    I recommend sticking with the projects in the kit and try to understand how they work. There are sound reasons why components are wired up as they show you. If you have questions about those circuits, ask them here. It will be fun discussing them..
     
  17. Mar 14, 2008 #16
    FET's blowing up are one of the nastiest. Not only it is loud and take crap out of you but may affect other active components so probably have to change them all.
     
  18. Mar 16, 2008 #17
    Electrolytic's Do not like current in their "wrong" direction for long periods of time. Some people are mistaken though when they think that an electrolytic will not work where there is an oscillating circuit going through them, they are still capacitors, they work like any other typical capacitor, they just have longevity problems when too much current is going through them the wrong way.


    Also you will notice on the top of most electrolytics, they have a crimped pattern where if the pressure gets too high they will open up through that route. If you get worried about working with them, just aim them away from your face!

    always where safety glasses!
     
  19. Mar 18, 2008 #18
    Would capacitors still explode if it's in the right direction but the voltage is over the limit?
     
  20. Mar 18, 2008 #19
    Yes. Caps have rated voltage.
     
  21. Mar 26, 2008 #20
    lol yeah :D I've never blown a capacitor before, but had my fair share of transistors before I learnt to bias them properly! Theyre boring though, they just stop working... no explosion.
    All transistors should contain a little gelignite to let you know when you've messed up!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Exploding capacitor
  1. Working of capacitor (Replies: 3)

Loading...