[urq] Electrical Experts - Question re. Capacitor installation

Ben Swann benswann at verizon.net
Wed Oct 31 08:32:08 PDT 2007

This one looks correct to me:

ation.htm  and I did not see it until I searched today


That is supposedly like B in the ASCII diagram below:


A, Battery + powercable  (+)_ -------------  (+) cap (-)  ----------- (+) amp --|||->

or like this 

B, Battery + powercable  (+) -------- (+) cap (-)-----------|||-> Ground


                                                    (+)amp (-) -----------|||-> Ground

However, I have seen several apparently misleading diagrams in prior searches that show
A  on the installation diagrams.  This was on diagrams from either manufacturer or
distributor, so that is the main reason I wanted to clarify.  Funny thing is I'm not
finding the confusing/incorrect diagram now.



From: Mike Sylvester [mailto:mike at urq20v.com] 
Sent: Wednesday, October 31, 2007 10:55 AM
To: Ben Swann
Subject: RE: [urq] Electrical Experts - Question re. Capacitor installation


Putting a cap in series with a the power feed of an amp will not work.

Something is definitely different than you are describing.


www.urq20v.com <http://www.urq20v.com/> 

-------- Original Message --------
Subject: Re: [urq] Electrical Experts - Question re. Capacitor
From: "Ben Swann" <benswann at verizon.net>
Date: Wed, October 31, 2007 10:42 am
To: "'LL - NY'" <larrycleung at gmail.com>
Cc: 'URQ' <urq at audifans.com>,  quattro at audifans.com

Well I definitely don't want this acting like a choke - this is not points or
hall-effect trigger. I would be using this as a stiffening capacitor, partially to
compensate for inadequate wiring - even if the wiring is truly sufficient. I merely
want to assure more than adequate power delivery to the coil even when there are power
lags elsewhere, especially when running at very high RPM, eg. 8000+. The circuit should
also have adequate reserve to pop the injectors open too.

Of course I'll have one supplying the power amp in the rear of the car too. I saw a
diagram that showed a cap in series to a power amp - I think it was a 4 farad. That did
not make sense that the cap was wired with no other + feed. Would that be a correct
hookup to an amp? Does having it in parallel have a detrimental effect, or is the
series wiring not necessarily a good idea?

Just trying to gain a more practical understanding of using power supply capacitors.



From: LL - NY [mailto:larrycleung at gmail.com <> ] 
Sent: Wednesday, October 31, 2007 10:19 AM
To: Ben Swann
Cc: quattro at audifans.com <> ; URQ
Subject: Re: Electrical Experts - Question re. Capacitor installation

A cap installed in a series in a DC circuit will not pass 
current until the circuit is actually shut down. It MUST
be wired in parallel to be used as a part of a filter system
for a DC power source. Choke Coils, OTOH should be
installed in-line (series). 

The idea for both devices is to make the DC that goes
to the head unit (or amp) more DC like, as they act as
dampers to voltage (and by I = V/R) and current fluctuations. 

That being said, when we broke down one of our Magnetizers
at work, I took a HUGE (as in 1.2 Farad) cap from the machine
to use as a filter on my 4KQ's rear amp. It was meant for 
huge currents (around 200 Amps) at voltages well above 
automotive use (120V). Net filtering effect. Virtually nothing. 



On 10/31/07, Ben Swann <benswann at verizon.net <> > wrote:

I found this article to be helpful and shows the concept I was referring to:


It looks like installing in parallel is OK, just need to be careful about initial 
charging and discharging.


From: Ben Swann [mailto:benswann at verizon.net <> ]
Sent: Wednesday, October 31, 2007 8:24 AM 
To: quattro at audifans.com <> ; 'URQ'
Cc: 'Ben Swann'
Subject: Electrical Experts - Question re. Capacitor installation

Something new to my realm of expertise. 

I would like to install an electrolytic capacitor to act as a buffer for an ignition
system - sort of like placing a second battery up close to the load.. Since the
distance of the battery to the coil is about 7-8' and my understanding that a circuit 
may lag, it seems installing a large capacitor might be a good idea. If so, it makes
sense that I'd install it in parallel with respect to feed wire and ground, however
diagrams for most stereo AMP installations show the cap to be inline, with no other 
current path to the amp.

Is it OK to install an electrolytic cap. as sort of a buffer or quick discharge
batteryin parallel with the circuit? That is basically to connect the positive end to
battery post near load and ground as normal, leaving the original positive feed path 
intact. I have some 1 and 2 Farad caps and this is mainly to prevent lag at high RPM,
similar to stereo clipping at high volume.

Good Idea or ??? I'm doing some searches, but not finding a solid answer. 



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