Re: caps (was: 8250LP....)

> Did they really use electrolytic caps for bypasses in the eighties?

Bypass capacitors are filters to remove any AC component from a DC signal, which has in fact always been the main application for electrolytics. 

Whether to use electrolytics (or tantalums, MLCCs etc.) or ceramics etc. depends on the frequency you want to bypass/filter; many times you will find an electrolytic bypass capacitor in parallel with ceramics, each one(s) filtering different frequencies.

Tantalums have their own issues with absorbing moisture and shorting out, often catastrophically, so in most cases (as Francesco suggests) MLCC caps are probably the best modern electrolytic replacement these days.

m

----- Original Message ----- 
From: <silverdr@wfmh.org.pl>
To: <cbm-hackers@musoftware.de>
Sent: Monday, August 21, 2017 10:12 AM
Subject: Re: caps (was: 8250LP....)



> On 2017-08-21, at 13:51, Francesco Messineo <francesco.messineo@gmail.com> wrote:
> 
> sorry to jump into this discussion (I wish I owned either a 1001 or
> 8x50 myself...), but assuming the leaky capacitors are electrolytics,
> they can nowadays almost always be replaced with MLCC capacitors that
> are both tiny and last forever.
> Of course one should examine the actual circtuit to be sure, but if
> they're the usual (for the '80s electronics) supply bypass or DC block
> ones, the MLCC will work even better of the original.
> I wouldn't dare using an MLCC in place of electrolytic as a switcher
> output capacitor unless I really checked what I'm doing anyway.

Did they really use electrolytic caps for bypasses in the eighties? I haven't had much experience in the pre 1982 (pre-C64 that is :-) electronics but those I've seen since 1982 were using ceramics for bypasses. DC blocks - yes, I've seen those. As for replacing the aluminium electrolytic ones, I heard about tantalum ones being the best (?) replacement for the aluminium based polarised caps.

-- 
SD! - http://e4aws.silverdr.com/


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