[sdiy] caps -- NPO or NP0?

[asfi at eol.ca]

Quoting john mahoney <jmahoney at gate.net>:

> It actually says non-polarized there, which may be where I got that
> impression. (Of course I read all of the documentation before starting
> this project, right?! Ahem... ;-)
> 
> The cap wasn't *too* hard to find, if C0G is really the same as NP0.
> For the curious, Kemet makes them and Mouser has them for 36 cents
> each, part #80-C430C222J1G:
>
>
http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=346699&e_categoryid=297&e_pcodeid=64601

Unfortunately, that's not the animal you're looking for -- this Mouser
part is actually a 2.2nF capacitor. There's a typo in the catalogue
listing.

A 1uF NP0 (or C0G) capacitor is going to be large and impossibly
expensive, assuming it even exists. Generally, applications requiring
close tolerances on capacitance (filters, oscillators) usually need them
with values < 1nF. Larger values are used for DC blocking, ripple
filtering, and that sort of thing, where +/- 10%, 20%, or even 80%
over temperature range isn't a big deal.

"non-polarized" IS what you need, however.

- Colin Hinz
  Toronto, Canada

Cheeky postscript: is the American electronics industry going to discover
the nanofarad this century? Just wondering.