Is this capacitor np0/c0g?

[xefe]

Sorry for the dumb question but i couldn't find conclusive proof about this matter on the web.
What i want to know if a ceramic capacitor disk (classic old school shape) that only has 8.2 printed on it (8.2pf) but also has a black mark on the top of it, really is a np0 type.

Looks like this one:

Sorry if it is the wrong place to ask.

thanks.

 

[JohnRoberts]

I am not aware of the black mark having any such meaning.

The best way to determine that it is a cog cap is to buy a cog cap from a reputable vendor.

JR

 

[Rochey]

I was always under the impression that NP0/COG really is an SMD thang.

However, having been burnt by grey market vendors on "COG" caps, I have to agree with John... if your not buying an exact line item from the likes of mouser/digikey/farnell, you could be getting Y5V junk dressed as COG/NPO.

Having said that, if you need passive components for things like power supply decoupling, logic interface type stuff... shady grey market guys are excellent. ($3 for 5000 peices of pulldown resistors anyone?)



/R

 

[ricardo]

While I agree with JR that COG/NPO caps are so cheap & readily available that you might as well buy some new ones, there is a simple check if you are really skint.  I'm a real beach bum but even I'm not as skint as that. 

Measure your cap with a good DMM.  (Caveats about cheap DMMs with poor resolution on capacitance scale bla bla)
Put it between finger & thumb to warm it up.
If its not COG/NPO, the value will change.
Note : 8p2 is so small that just moving the cap will change the capacitance of your connecting leads.

Just shows how bad non COG/NPO ceramics are  8)

BTW, most 8p2 ceramics will be NPO but don't rely on this for life support stuff.

 

[xefe]

http://www.sentex.ca/~mec1995/gadgets/caps/caps.html
http://kd1jv.qrpradio.com/ARRLHBC/ARRL_MMR40.html
http://www.w1hue.us/Articles/CUB3.html
http://salviusrobot.blogspot.pt/2012/06/capacitors.html

a quick googling gave me this results. all those sites refer to the black marking on top as being np0.

EDIT:
also this vishay datasheet:
http://images.vishay.com/books/VSD-DB0012-0011_Ceramic%20Singlelayer%20Capacitors_INTERACTIVE.pdf
and this one:
http://www.eaa.net.au/PDF/Ceramic/Class1.pdf

 

[PRR]

> impression that NP0/COG really is an SMD thang.

Youngster.

Tempco near zero is mentioned in RDH 4th (pg 196), 1952; though not as "NP0".

I know NP0 has been around a lot longer than SMD.

> not aware of the black mark having any such meaning

FWIW? (One of xefe's citations)

http://www.sentex.ca/~mec1995/gadgets/caps/caps.html
"NPO" is standard for temperature stability and 'low-noise', it does *not* mean non-polarized even though you might think so because the abbreviation looks similar. Polarized ceramic capacitors do not exist.  The abreviation "NPO" stands for "Negative-Positive-Zero" (what is read as an 'O' is actually zero), and means that the negative and positive temperature coefficients of the device are zero--that is the capacitance does not vary with temperature. ONLY the black top indicates NPO qualification and the values are in the range from 1.8pF to 120pF, unless manufactured with different values for Military and/or industrial purposes on special request.

 

[JohnRoberts]

Your links didn't open for me, so I am still not aware of black marks on caps meaning NPO/COG

And yes I do know what those are.

Believe whomever you want this is the internet so I could be a dog... or a teenaged girl.

JR

 

[PRR]

> Your links didn't open for me

Which/whose links? xefe's first 4 links open for me, some slow.

> I could be a dog... or a teenaged girl.

Meet me behind the seafood shack at midnight, we'll open our "links", honey!

 

[xefe]

All my links open perfectly over here.

I posted 2 datasheets but i actually i found a couple more with reference to the black top being np0 temperature coefficient.

What other possibilities could exist to meaning of the black top, John?

thanks.

 

[JohnRoberts]

All my links open perfectly over here.

I posted 2 datasheets but i actually i found a couple more with reference to the black top being np0 temperature coefficient.

What other possibilities could exist to meaning of the black top, John?

thanks.

Ok today I was able to open the vishay link... in the general information they say the black mark mean NP0 for class 1 caps and n150 for class 2 caps. However class 2 caps do not come in less than 100pF values so I concur that your cap is probably class 1 and NPO (if vishay).

Good luck.

JR

I was not aware of these color codes but frankly