Subject:
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Re: Choosing Parts?
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Wed, 21 Apr 1999 13:18:38 GMT
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Original-From:
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Tom Brusehaver <tgb@cozy.core.wamnet.com=StopSpam=>
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Reply-To:
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TGB@WAMNET.COMsaynotospam
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Viewed:
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1034 times
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> For electrolytic capacitors, you want the printed voltage to be the
> closest voltage above the voltage you are operating at. The voltage listed
> on the can is the one it works best at.
I don't mean to be harsh, but this isn't exactly correct. The voltage
is the highest the capicitor is rated for. if you have a 12V circuit
it won't hurt to put in a 200V cap, but you'll need lots of room.
Generally for safty, in high current applications, most people will
take the highest voltage expected, and double it, and use that sized
cap.
> Careful with the polarity. Reversed
> polarity will cause the capacitor to heat and deform. Large voltage in
> reverse polarity will cause the capacitor to explode.
Even correctly polarized, with too high a voltage, they can come
apart. There is a substance like toothpaste in some electrolytics,
that will expand when heated (like a steam engine). The cans are
sealed with little holes to minimize the chances of voilent
explosion.
When I was younger I bought a RTTY demodulator at a ham flea market,
that had tubes in it. It was homemade by the guy I bought if from,
but it worked. One night my dad was copying some great stuff, and I
heard a ka-pow!!! I ran downstairs to see my dad with fuzzy paper bits
in his hair, eyebrows, moustaces, and all over his clothes. One of
the caps in the demodulator was rated at too low a voltage, and blew
up from the load. The demodulator case kept the can inside, but the
paper bits went everywhere. It is funny now, but then, I think it
scared all of us. I never got the demodulator working again.
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Message is in Reply To:
 | | Re: Choosing Parts?
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| In a message dated 4/21/99 1:08:33 AM Central Daylight Time, josr0633@cetus.zrz.TU-Berlin.DE writes: jos runarko: (...) For electrolytic capacitors, you want the printed voltage to be the closest voltage above the voltage you are operating at. The (...) (25 years ago, 21-Apr-99, to lugnet.robotics.handyboard)
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