Re: gEDA-user: electrolytic capacitors

[Gene Heskett <gene.heskett@xxxxxxxxxxx>]

On Saturday 27 December 2008, Robas, Teodor wrote:
>Do not count on this kind of capacitors:
>
>http://deep-blue.ro/tmp/chinese%20capacitor.jpg
>
>:))

What a ripoff.  No way in hell that would last more than a day, if that long 
with 50 volts of bias on it, (I'd guess 10 minutes max) and I'd have doubts 
even the dual can would contain the debris.

I take it you got curious when incoming QC said they weren't in spec?  BTW, 
that is a neat opening of the can you did.

They can explode pretty violently, so let me tell you a story.  Back in the 
mid-60's I came across a tube type, mobile cb radio that had to be one of the 
few attempts to build one for a 6 volt vehicle system, and predated the old 
Johnson whiteface by probably 10 years.  My pickup at the time, a 52 ford, 
had long since been converted to 12 volts, and I was in the radio, on the 
kitchen table, moving wires to convert it to 12 volts.  I missed one without 
realizing it, and had it running on a 12 volt supply for test.  It worked 
really really well, talking to the neighbors on a piece of wire laying on the 
floor for an antenna.  But after about 15 minutes the main filter capacitor 
let go, and the top of the can put a quarter sized print in the plastered 
ceiling that was about 1/4" deep.  I'm glad I wasn't in front of it at the 
time, else I might have been seriously injured.  I tried with a 20 oz hammer 
and could not put a dent that deep in that plaster with it.  Putting my meter 
on the stubs of the cans terminals I found the supply was making a hair over 
785 volts, and the can carried a 450 volt label.  I cleaned up the mess, 
replaced the cap, and found the other 2 taps on the transformer that I had 
missed, and ran that radio till I finally got a transistorized one.  But my 
kids, who were upstairs in bed at the time, have always said, somewhat tongue 
in cheek, that daddy was shooting at them. :)
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-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The best diplomat I know is a fully activated phaser bank.
		-- Scotty


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