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Electrolytic cap. Question

Discussion in 'General Electronics Discussion' started by siriusme, Dec 12, 2011.

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  1. siriusme

    siriusme

    1
    0
    Dec 12, 2011
    First Hello Everyone!

    Im working on a project of mine and my multimeter got broken. Then I decided to use 3v battery with a LED to test my circuit. After some short tests I realized that I have may given reversed polarity to my DC filters (3x3300uF 63V, 2x100uF 63V 1uF 63V caps.)
    My question is did I damaged them because I cant see any signs for problems for now?

    Thanks in advance!
     
  2. electro_pa

    electro_pa

    16
    0
    Aug 14, 2011
    Hi siriusme,
    Sorry about the meter!
    You are not likely to do permanent damage to that list of electro's with only 3volts and short time tests.
    You might damage the LED. Some LEDs only tolerate less than 2 volts directly without current limiting resistor.
    Are you working with an ex. PC style power supply?
    Many have been made with faulty/counterfeit, Asian-made electrolytics in past 10 years. Learn about this widespread problem at:http://en.wikipedia.org/wiki/Capacitor_plague
    Good luck with your project.
     
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,480
    2,826
    Jan 21, 2010
    I think the capacitor plague is a little overblown. Whilst there is little doubt that there are some dubious capacitors on the market, it is also true that around this time the design of motherboards etc changed to have a greater number of low voltage, high current rails. In conjunction with switchmode regulators this started to ask a lot more of capacitors.

    Electrolytic capacitors have a finite life, some as short as 500 hours (when used at the limits of their specification).

    Some of the problem has to come down to poor design.

    If you look closely at the specs of electrolytic capacitors you will find that they sometimes specify a maximum reverse voltage. In my experience this is often in the order of 10% of their forward voltage. It sounds like you were well under that.
     
  4. davelectronic

    davelectronic

    1,087
    12
    Dec 13, 2010
    All the above on over kill on bad caps is true, but there is still fall out from it today, ive lost a couple of pc's a dell and an hp, not to mention about 4 radios with bad capacitors in them, in the above cases the damage was not reversible, had i have spotted it earlier, well i doubt it.
    I think it will be years before its totally gone. But current capacitor stocks from suppliers seem fine, i would be warry of surplus stock or old stock, mass discounts on capacitors, one area where there still passing them off is in a model of cb radio, but the crafty buggers are using the same board in different models, so you think your getting a different radio.

    I took one back with bad capacitors in it, the shop i purchased from saw the problem, agreed it needed attention, emailed the supplier, they fobbed him off, he was good enough to replace the radio for a good known model.

    Personally i believe shed loads of gear ends up on what the radio forum guys call flea bay, funny bunch they are, like me, ha ha. :D
     
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