From: st1q9@rosie.uh.edu (Devine, Della M)
Newsgroups: rec.audio.car
Subject: Re: adding caps and a center channel
Date: 21 Jan 1993 08:19 CST
Organization: University of Houston
Distribution: world
NNTP-Posting-Host: rosie.uh.edu
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In article <C16y5M.K5p@news.cso.uiuc.edu>, jsc52962@uxa.cso.uiuc.edu (Jeffrey S. Curtis) writes...
>In article <20JAN199316312680@rosie.uh.edu> st1q9@rosie.uh.edu (Devine, Della M) writes:
>}The reason they recommended a resistor on the positive side was to
>}limit the current the cap pulled the instant it was powered on.
>}I didn't think it was a good idea until i first installed my
>}caps on my system. (just 240KmF for 220 watts).  I just hooked up the
>                          ^^^^^^
> 
>Well, there's your problem - you were using a 240 farad capacitor.  Where
>was it mounted - the trunk, or the roof?  ;-)
> 
>(I assume you meant 240KuF, or 240,000uF)
> 
>}positive to the terminal, screwed it in, then hooked up the negative
>}the instant i touched the ground to the cap my fuses blew..
>}mind you this was just the first one and it blew two 30amp fuses for this
>}amp. (it uses two 10guage wires with 30amps fused each for some reason..it's
>}an old , 3 years, linear power 2202).
>}this blew minmy mind!!!  60 amps!!!  te next one oi chatrged up with
>}a 10 ohm 10 watt resistor inline and it waarmed the resistor up but didn't
>}pul but about 1 to 12..that is 1.2 amps. (my delete dont work right now!)
>}anyway, the resistor saved me the 3 dollars for two new fuses again....
> 
>Ok, this seems like a fair solution to prevent the caps from rapidly
>charging and blowing your fuses.  The problem, though, is that it also
>prevents the cap from rapidly discharging, which is the reason it's
>there in the first place.  So what do you do? The first thing that
>comes to my mind is to have a switchable circuit that bypasses the
>resistor after the initial second or so that the cap will be charging.
>This should probably work out since the cap probably won't ever discharge
>to the point of needing to draw massive amounts of current fast (on the
>order of magnitude of when it first powers up).
> 
>If my thinking is completely off-base, I apologize - it's kind of late.
> 
>Jeff
>-- 
>Jeffrey S. Curtis sidewinder@uiuc.edu | "Resplendent and full again, they revel
> The Power of 37  free2207 at uiucvmd | in their role as self-appointed critics
> Sony - Phase Linear - Sanyo - Sennet | of the establishment..."
> Jensen - Polk - StreetWires - Proton |   -- INXS _Welcome to Wherever You Are_



No your thinking is not completely off base...
   You use the resistor to charge the cap then once it its charged you don't
ever have to charge it again as it will not usually becomre discharged enough
to the point of complete discharge so the resistor is no longer needed.
Just charge it up once using the resistor then pull the resistor off and
hook up striaght to the battery.

(excuse my crappy typing...the delete key don't work for some reason).

william c devine ii

reply to; wdevine@andrew.cea.pvamu.edu
      or: devine@pvhep.pvamu.edu


oh and yes i was using 240,000 uF caps..not 240 farad!  gawrsh.
Newsgroups: rec.audio.car