Capacitor questions

[List, Christopher]

On Sunday, August 02, 1998 3:40 PM, cmacdon at ix.netcom.com
[SMTP:cmacdon at ix.netcom.com] wrote:
> I apologize if this is a worn-out retread of an old topic, I'm a bit
new
> at this.
> 
> I am breadboarding a diode ladder filter and have bought polystyrene
and
> polypropylene capacitors for the project based on what I have been
> reading on various diy web sites (thanks a million to those of you who
> put those up BTW!).

My understanding is that Polystyrenes are generally the best - and the
radial lead ones come in a relatively small package from 560pF through
10nF (.01uF). Above that you start needing polypropylene. You will
notice that the "Metalized" polypro's in the Mouser catalog (the Xicons,
not the Vishay "Orange Drop") tend to be a "size" or two smaller than
the non-metallized, so I generally go for these.Also, if you can find
polypros with a voltage rating of 100VDC, they tend to be smaller in
size than the 400VDC models - so keep an eye out for that. The metalized
polypros are fairly usable - size wise - up to about .47uF - these are a
little bigger than .5" lead spacing (15mm). For anything bigger than
that in terms of capacitance, I usually struggle between what I want for
performance and what I need for size. I've tried different types in a
couple of applications and haven't noticed any difference.

My real point is that you can often find a good balance between size and
the type of cap you want just by diligently searching through all of
your catalogs.

::CList