🚀 go-pugleaf

garland@ohstpy.mps.ohio-state.edu writes:
: Here's an elementary question about capacitors that I'm almost too embarrassed
: to ask. Many audio circuits I've seen specify mylar, polystyrene, or paper 
: capacitors in the .01uF-.1uF range.  Is there some advantage these types of
: capacitors have (e.g., lower noise, more stability) over disk ceramics or
: silver micas? For instance, I got a bag of .01uF 400V mylar capacitors on
: close-out from a local parts distributor, but am not sure what I should use
: them for. Presumably, their self-inductance is too high for rf circuits, where
: I would normally use ceramics or micas, but are they suitable for general
: purpose bypassing, etc. of power supplies, op amp, and TTL circuits? Are they
: OVERKILL for such uses (i.e., is their temperature coefficient, tolerance, etc.
: so good that I'm wasting them for such applications?)  I'd appreciate any
: guidance. Thanks.
: 
: jim Garland
:  
:        
 
Sorry, I'm no expert either, probably shouldn't be posting this, but, here it
goes anyway ...

The MYLAR's themselves aren't really that much better than the polystyrene
capacitors. What the diagrams want to say is that one shouldn't use the
ceramic capacitors, since, for those capacities they can only be made of
Type III ceramics, which is non-linear. 

Personally, I would bypass the digital IC's with Type III ceramics, because
they are usually cheaper and smaller than the foil capacitors (MYLAR, poly, 
etc.) but would prefer the latter wherever the analog signals are involved.

The foil capacitors are usually employed in filter circuitry - again, for
their linearity - but, basically only in the AF range, because of their
inductivity.

I hope this helped.

Alby.