Monolythic / Multilayer 1uF capacitors

[Beo]

Two very affordable examples:

1UF 50V MULTILAYER MONOLITHIC CERAMIC CAPACITOR
http://www.taydaelectronics.com/1uf-50v-multilayer-ceramic-capacitor.html
12 cents

1.0uF 50V Multilayer Ceramic Capacitor
http://www.futurlec.com/Capacitors/C1000UMCpr.shtml
25 cents

So I've searched and read all the past discussions. I usually use poly box for 1uF, but it does make for some expanded layouts. Anyone want to comment on using multilayer monolithic ceramics for:
A. 1uF coupling
B. 1uF filtering (e.g. cap to ground)

The circuit I'm currently playing with is a compressor, so unintended distortion is a concern.
Thanks

[PRR]

"Capacitance for X7R varies under the influence of electrical operating conditions such as voltage and frequency."
https://www.avx.com/docs/catalogs/cx7r.pdf

Varies with voltage and frequency == Distortion.

I suspect it could work without audible problem. Depends a lot on where it is.

Also:
http://edn.com/design/analog/4416466/3/Signal-distortion-from-high-K-ceramic-capacitors
http://www.diyaudio.com/forums/parts/77299-ceramic-capacitors.html#post888172


I would steer clear.

[Beo]

Thanks Paul. Great links. I had to research X7R and NP0/COG. Also came across this thread:
http://www.diystompboxes.com/smfforum/index.php?topic=30558.0

One trouble with parts sourcing online is that it's not always clear what type of capacitor or material is used. My second link (Futurlec) doesn't specify and doesn't seem to have a datasheet... perhaps it is COG? If I understand correctly, using ceramics for higher value capacitance (i.e. 1uF) might be okay with NP0/COG caps, but not X7R.

[bool]

As a coupling cap, mlcc x7r "sounds" not quite dislike a tantalum cap. Slightly "harder" than tantalums, but not that much. But you aren't building a hi-fi component if you're asking around here, are you? ...

[PRR]

Small caps (under 1,000pFd/1nFd) can be (and usually are) made with C0G/NP0 stuff. It is good like glass, but easier to work.

Large caps (roughly over 1,000pFd) get too big/costly. Then they switch from pure/sweet G0G ceramic to a highly-"salted" ceramic which jazzes-up the capacitance but the capacitance you get varies with almost everything.

I remember when 0.01uFd was a "big" ceramic, and invariably a dubious capacitor. Fine if you just wanted "some" capacitance and were not too fussy how much, or if it varied with voltage or temperature. _I_ can sometimes hear one X7R capacitor in a hi-fi signal path.

They keep packing more into less, and 1.0ufd is apparently a stock item at low voltage (has been for years IIRC). But it is surely in the "highly salted" class and will be less signal-linear than a nice paper (plastic film) cap.

As Bool says, a big ceramic won't get you laughed off stage. A few classic guitar amps owe some of their flavor to ceramics. Most of the audience won't know the difference.

[armdnrdy]

Since we're on the subject of ceramics, and we have the attention of a knowledgeable person....

I've been trying to find info on the old Japanese ceramic codes without much luck.

Does anyone know what KCK represents? For example 240pf KCK.

Also, I posted a question about a year or so ago but didn't really get a reply that I was comfortable with.

In the Roland AP-7 Jet Phaser service manual there is a side detail on laying ceramic capacitors over resistors. In my thread, I got answers like...it doesn't matter, or they are bent over for clearance. Well...the AP-7 is housed in a huge enclosure, so I doubt if it's a clearance issue, and I don't know why Roland would draw a detail in a service manual for something that doesn't matter!

I was wondering if it may be a way to reduce piezoelectric effect from the ceramics.

Thoughts?

[PRR]

> what KCK represents?

Google??

http://www.mmeth.co.th/Company%20History.htm --First line

http://pdf.datasheetarchive.com/indexerfiles/Scans-063/DSA2IH00128252.pdf --Bottom table, maker cross-reference

[armdnrdy]

I found that during my search. One problem though.


Nov. 1987 Established company As "KCK Ceramics Capacitors Limited

Roland AP-7 Jet Phaser 1976

These caps with the label XXXpf and KCK below it are in all of the Jet Phaser gut shots that I've seen.

[PRR]

> Nov. 1987

I was wondering.

Odd coincidence though.

For now I sit on the idea that before they got their "KCK Ceramics Capacitors Limited" papers, it was 'KCK Crockery and Capacitors" in a back-alley.

[armdnrdy]

For now I sit on the idea that before they got their "KCK Ceramics Capacitors Limited" papers, it was 'KCK Crockery and Capacitors" in a back-alley.

Very well could be!

Having a capacitor company the same name as an old capacitor code sort of messes things up a bit for finding info!

One thing I did notice...I think the KCK company printed those letters above the value with other info below.

The old code KCK is printed below the value from what I've seen.

[amz-fx]

Interesting video about ceramic capacitors:

regards, Jack

[amptramp]

Check out the nonlinearity in the ceramic LV scope trace shown here:

http://www.jacmusic.com/techcorner/SBENCH-PAGES/sbench102/caps.html

[armdnrdy]

Thanks for that Jack & Ron.

Very informative.

I'm amazed that ceramics are used for things like setting frequency in oscillators!

[R.G.]

I'm amazed that ceramics are used for things like setting frequency in oscillators!

COG

[armdnrdy]

I'm amazed that ceramics are used for things like setting frequency in oscillators!

COG

Now you tell us! 

I'm sure that you outlined it in a thread somewhere.

Good to know! This info will make a difference in ceramic cap choices for future builds. If a schematic called out for a ceramic cap, I would just throw in whatever cap was available...haphazardly!

[R.G.]

Well, there are (as always) some subtleties.

The three-character ceramic type relates to the thermal characteristics of the ceramic cap. COG (also called NPO) is the temperature stable stuff, and also more other-stable. You pay for that in that the dielectric constant of type COG ceramics is not as large as the less-stable types, and so COG is really only practical up to about 1000pF. There are several other types, each getting you more capacitance per unity volume and less stability - of course. Mother Nature is not about to let you get away without paying the freight. The wild-eyed, capacitance-value-is-everything stuff is, like in people, less stable and in general more shifty.

Here's a decent intro to the ceramic capacitor classes and the subclassifications.  Z5U - the shifty one - can vary hugely with temperature and other conditions. It's used mostly for bypassing power supplies, with its shifty friend, electrolytics.

[puretube]

VCCs for LFOs... 

[Beo]

thanks everyone. I know more about ceramic types than I did at the start. The other part of my original question was the sensitivity of using large value ceramic caps (or for that matter electrolytics if they are also "shifty") as signal coupling caps vs filters to ground. Is there a bigger bang for the buck in using film caps for signal coupling caps than there is for caps to ground? I generally use 1uF film box caps even for connections to ground, if for no other reason than longevity.

[amptramp]

Some of the higher dielectric constant ceramics are microphonic, which may not show up in a test but may show up at a gig where there is a lot of noise.  These materials tend to be piezoelectric and will respond to sound.