Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!husc6!cmcl2!ccnysci!sukenick
From: sukenick@ccnysci.UUCP (SYG)
Newsgroups: sci.electronics
Subject: Re: Substituting Caps oin Logic Supplies
Message-ID: <2116@ccnysci.UUCP>
Date: 31 May 89 20:14:30 GMT
References: <484@dalek.UUCP> <1989May24.154332.29113@utzoo.uucp>
Reply-To: sukenick@ccnysci.UUCP (SYG)
Organization: City College Of New York
Lines: 19

In article <1989May24.154332.29113@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes:
>In article <484@dalek.UUCP> sjb@dalek.UUCP (Seth J. Bradley) writes:
>>... The question is, are the new ultra-high caps
>>(i.e. 3.3F at 5.5 V) which are designed for power backup
>>suitable for use as power supply filter capacitors?

>In general, no -- their internal resistance is too high.  Substantial
>currents flow in and out of filter capacitors during the AC cycle.

Since Seth wants to use these caps for power backup, pehaps keep the original
filter caps in place and put the 3.3F after the filter caps or
(if that will cause problems with the power supply, then perhaps)
in parallel, if the voltage specs
at that point are acceptable:  5.5V might cut it close, although for less
cap., you could  use two of them in series.  The filter caps will filter
when power is ok; when AC power goes down, the 3.3F will supply reserve power.

(ie: the PS caps are the 60 Hz filters; the  3.3F does the low low frequency
(power outage) filtering :-) )