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AndrewT 7th April 2006 10:09 AM

ceramic capacitors ?
 
Hi all,
what is the difference between NPO and COG ceramic capacitors?

How might it affect their intended end use?

mzzj 7th April 2006 10:20 AM

Re: ceramic capacitors ?
 
Quote:

Originally posted by AndrewT
Hi all,
what is the difference between NPO and COG ceramic capacitors?

How might it affect their intended end use?

Nada, they are same thing. And its NP0 and C0G, not NPO or COG
"Negative-Positive-Zero" as tempco is +-30ppm :)

AndrewT 7th April 2006 11:27 AM

Thanks Mzzj,

What is C0G?

jacco vermeulen 7th April 2006 02:48 PM

COG is the name of the dielectric type.

serengetiplains 7th April 2006 05:03 PM

C0G capacitors have excellent dielectric characteristics which compete with better film varieties: low distortion, low DA, low DF. X5R capacitors, and its siblings, are another matter entirely having dielectric characteristics that compete with the worst of electrolytics for Worst Capacitor Ever.

serengetiplains 7th April 2006 05:39 PM

2 Attachment(s)
Seeing as I mentioned the dreaded X5R, here's a distortion plot of an X7R. Says Cyril Bateman who performed the test generating the plot:

"This 10nF X7R ceramic was made by a CECC approved, European manufacturer. It was tested at 1kHz and 3 volts, in series with a 10k ohm current limiting resistor. Measurable distortion exists at all voltages down to 0.5 volts my lowest test voltage."

serengetiplains 7th April 2006 05:53 PM

2 Attachment(s)
Here's the same test on a C0G.

RetroAudio 7th April 2006 06:16 PM

I've been using NPO/COG caps in a variety of places with extremely good results,..at least to the ear.

AndrewT 7th April 2006 06:29 PM

Hi Serenq,
that's some difference -63db (x7r) reduced to -127db for the C0G.

Thanks to all.

Is the low distortion an indication that ppm/V is not an issue for C0G and NP0 when used in Audio locations. We all use ceramic in bypass duty.

infinia 7th April 2006 06:30 PM

Hi Tom,
Thanks for the plots. Do you have the test configuration diagram?

Too bad ceramics a got a bad rap in the audio world. They are really good performers if used properly. But can a nightmare if misused. (piezo microphonics). I still use em X7R included and could not be without.
Generally use for low imp/supply bypass. Never in high imp/ high gain circuits like feedback networks. NP0's abound in RF world up to several GHz.


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