[sdiy] comprehensive guide to visual identification of capacitors

[anthony]

I was wondering if anyone knew of a comprehensive guide to visual 
identification of capacitors? I have seen a few decent guides that DESCRIBE 
the various kinds, but I've found very little in the way of showing what 
they might look like - a lot of  examples side-by-side. I know some look 
very similar so showing how one could be easilly confused with another would 
be good too. As well as examples of how the same type can look very 
different.
I have a lot of different kinds of capacitors. Some of them I think are 
pretty good, but I'd like to know what type they are. Maybe I could describe 
some and people can chiem in what they think.

I have some Spragues that I'm pretty sure are polycarbonate. They're kind of 
big and they look like someone rolled them up and stuck epoxy on the ends. I 
like these. I have some Atoms. I like these too.

But those are easy ones. The film caps are tricky. I have lots of caps that 
look like little plastic boxes, potted with epoxy. Some of them look pretty 
good - and I know that they came out of expensive test gear. Some of them 
don't look as good. I try to go by tolerance - I figure it's a good one if 
it's a J or K. I have a few even better. I think that these are 
polypropylene, but I'm not sure.

Then there are greenie weenies (sometimes they're brown). I assume these are 
mylar. These are the tall skinny ones. Others that are short and fat I think 
are a better film type. I go by ratings. Other short and fat ones are mylar 
also though.

I have some Panasonic film caps that look like they have the same coating 
that ceramics have. I'm not sure if I'm being clear. They tend to be a 
little on the big side for their rated values. I could post some examples 
with my web cam maybe.

What I'm after is a better way to sort out the ones that'd be good for audio 
and timing - from the other general purpose. I have an idea of what they 
are, but I'm not sure. I'd like to know if there's a sure-fire way to tell 
if one is say a Teflon or a polycarbonate type (some of the scientific gear 
I've parted out could easilly have had some). Presented with different 
examples of what to look for would help.

I think with everyone's help - if such a comprehensive list does not exist - 
I will make one.