used to know but dont remember- what do the "Z5U" or "NPO" on crapacitors mean?

[N3DRB The Derb]

all the disk caps I got offa ebay ( .01uf @ 3KV) to finish the amp with also have "Z5U" on em. What the hell does Z5U mean?

[Jim, W5JO]

Here is a brief discussion on Z5U and a chart that will allow you to determine all those letters.

http://en.wikipedia.org/wiki/EIA_Class_2_dielectric

[N3DRB The Derb]

thank you Jim.

[VE7 Kilohertz]

NPO is a better spec part, less temperature drift and is usually associated with 5% tolerance parts. Z5U has a lot more drift with temp change and is usually a 20% tolerance part. There is one other spec in between these X7R and is usually a 10% part.

Cheers

Paul

[K1ZJH]

It is the dielelectric. To really nitpick,  Z5U capshave piezzo electric effect. Varying voltage will change the capacitance. If I was a really, really picky audiophile, I'd never use a Z5U for audio coupling..

Pete