how good are ceramic capacitors ???
what is the range of application ???
we often hear that ceramics for input filters ,miller caps, feedback traces are better to be mkt or styroflex or silver mika ....( eventhough ceramics exist in comercial application )
then if its a low fi application like small psu with 7812 or 7805 is it ok to use there as decoupling or over the rectifier ????
thanks
what is the range of application ???
we often hear that ceramics for input filters ,miller caps, feedback traces are better to be mkt or styroflex or silver mika ....( eventhough ceramics exist in comercial application )
then if its a low fi application like small psu with 7812 or 7805 is it ok to use there as decoupling or over the rectifier ????
thanks
Hi,
there are two downsides to ceramic that I'm aware of.
1.) capacitance varies with applied voltage.
2.) Non NPO/C0G vary capacitance and other parameters with temperature. NPO/C0G vary their other characteristics just like the hiK versions with temperature.
If you keep the voltage constant (eg. supply decoupling) most of the disadvantages of 1.) are avoided.
Some designers swear by ceramics for local or on pin decoupling. Even to the extent of recommending the high K specifically for this use.
I think everyone is agreed that ceramics are not good at passing Audio Signals.
Few, if any, other capacitor types can challenge the low inductance of ceramic. If low inductance dominates your requirement, then possibly ceramic might be your only solution.
there are two downsides to ceramic that I'm aware of.
1.) capacitance varies with applied voltage.
2.) Non NPO/C0G vary capacitance and other parameters with temperature. NPO/C0G vary their other characteristics just like the hiK versions with temperature.
If you keep the voltage constant (eg. supply decoupling) most of the disadvantages of 1.) are avoided.
Some designers swear by ceramics for local or on pin decoupling. Even to the extent of recommending the high K specifically for this use.
I think everyone is agreed that ceramics are not good at passing Audio Signals.
Few, if any, other capacitor types can challenge the low inductance of ceramic. If low inductance dominates your requirement, then possibly ceramic might be your only solution.
thanks andrew
the thing is that i got about 10.000 ceramics of any size and capacitance .... and it seems that i have to start using them somewhere cause i am runing out of time ....
i am not going to construct things in this life that will consume 10.000 ceramics .....
the thing is that i got about 10.000 ceramics of any size and capacitance .... and it seems that i have to start using them somewhere cause i am runing out of time ....
i am not going to construct things in this life that will consume 10.000 ceramics .....
Ceramic capacitors can be useful. They are fine for supply bypassing, especially the SMT types which have very low inductance. You must consider what the actual capacitance will be at the voltage you use them at - look at the datasheet.
You might find it interesting to look at Cyril Bateman's article on capacitor distortion, which you can find on his website. It shows that C0G ceramic capacitors have very low distortion, while other types are very bad and thus should not be used in the audio path if you're at all concerned with sound quality.
You might find it interesting to look at Cyril Bateman's article on capacitor distortion, which you can find on his website. It shows that C0G ceramic capacitors have very low distortion, while other types are very bad and thus should not be used in the audio path if you're at all concerned with sound quality.
Hi Saki
It is true that some types (e.g. CD15 +/-1% series of Cornell Dubilier for 1,26 GBP/piece excluding VAT) of silvered mica caps offers great stabillity under any condition. This is usefull in timing circuits or other close tollerance applications like in filters included of course the Miller pole compensation etc.
Nothing more, nothing less. I have used them in my last amplifier project and i had a small improvement (it is very difficult to hear) in high frequencies. OTOH i had a great visual improvement on my project PCBs appearance 😀 😀 😀
All above mentioned by Andrew, i think are very explanatory.
Fotis
It is true that some types (e.g. CD15 +/-1% series of Cornell Dubilier for 1,26 GBP/piece excluding VAT) of silvered mica caps offers great stabillity under any condition. This is usefull in timing circuits or other close tollerance applications like in filters included of course the Miller pole compensation etc.
Nothing more, nothing less. I have used them in my last amplifier project and i had a small improvement (it is very difficult to hear) in high frequencies. OTOH i had a great visual improvement on my project PCBs appearance 😀 😀 😀
All above mentioned by Andrew, i think are very explanatory.
Fotis
Lumba Ogir said:
Yes, even if you care about the sound. You just have to be aware of the properties of the capacitors you are using, e.g. don't use high-k types anywhere that linearity matters, but C0G types are fine for all sorts of purposes, e.g. they work fine as Miller compensation capacitors.
Some multilayer C0G types are about as perfect as you can get, even with temperature. Low DF and low DA. They just don't come in high values nor are they very size efficient. Chances are you've got hi K parts good for bypassing, so maybe build a lot of digital circuits?
Quoting from Cyril Bateman:
"‘Ceramic’ covers an extremely wide range of dielectrics. In the seventies the Erie Company produced more than fifty different capacitor ceramic formulations, sub-divided as Class 1 (non-polar) or Class 2 (polar) according to the materials used.
Class 1 ceramics do not contain Barium Titanate, so have a low ‘k’ value. The best known is C0G. With its controlled temperature coefficient of zero ± 30 ppm, it was originally called NP0 by the Erie Corporation. It is non-polar and has a small dielectric absorption coefficient. From my tests it has almost no measurable harmonic distortion. COG ceramic is more stable with time and temperature than mica capacitors and from my tests COG can produce less distortion.
C0G ceramic provides the most stable capacitance value, over long time periods and temperature excursions, of all easily obtained capacitor dielectrics. It is frequently used as a capacitance transfer standard in calibration laboratories. Yet as a small disc capacitor it costs only pennies. Assembled as a multilayer, it can provide capacitances of 100 nF and above, rated for 100 volts working, and much higher voltages for smaller capacitances.
Other Class 1 ceramics, sometimes called ‘low k’, provide increased capacitance within a controlled temperature coefficient, e.g. P100, N750 etc. in ppm. These also are non-polar and exhibit little dielectric absorption. I have tested up to N750, sometimes called U2J, and found very low distortion."
One clear problem with hi-k ceramics is that they are microphonic. While probably all caps have some degree of this, Class II ceramics are particularly afflicted since they are made with barium titanate, a piezoelectric material. Prof. Leach once told me he heard them audibly singing in circuit as lag caps when he was testing an amp. Since Class I ceramics (C0G) are not made out of barium titanate, they should not be as microphonic. However, I have not been able to find any info on just how microphonic or not they are.
"‘Ceramic’ covers an extremely wide range of dielectrics. In the seventies the Erie Company produced more than fifty different capacitor ceramic formulations, sub-divided as Class 1 (non-polar) or Class 2 (polar) according to the materials used.
Class 1 ceramics do not contain Barium Titanate, so have a low ‘k’ value. The best known is C0G. With its controlled temperature coefficient of zero ± 30 ppm, it was originally called NP0 by the Erie Corporation. It is non-polar and has a small dielectric absorption coefficient. From my tests it has almost no measurable harmonic distortion. COG ceramic is more stable with time and temperature than mica capacitors and from my tests COG can produce less distortion.
C0G ceramic provides the most stable capacitance value, over long time periods and temperature excursions, of all easily obtained capacitor dielectrics. It is frequently used as a capacitance transfer standard in calibration laboratories. Yet as a small disc capacitor it costs only pennies. Assembled as a multilayer, it can provide capacitances of 100 nF and above, rated for 100 volts working, and much higher voltages for smaller capacitances.
Other Class 1 ceramics, sometimes called ‘low k’, provide increased capacitance within a controlled temperature coefficient, e.g. P100, N750 etc. in ppm. These also are non-polar and exhibit little dielectric absorption. I have tested up to N750, sometimes called U2J, and found very low distortion."
One clear problem with hi-k ceramics is that they are microphonic. While probably all caps have some degree of this, Class II ceramics are particularly afflicted since they are made with barium titanate, a piezoelectric material. Prof. Leach once told me he heard them audibly singing in circuit as lag caps when he was testing an amp. Since Class I ceramics (C0G) are not made out of barium titanate, they should not be as microphonic. However, I have not been able to find any info on just how microphonic or not they are.
Beside all that was mentioned in this thread, all ceramics exhibit, more or less, piezoelectric effect. Any vibration will kill your sound.
If you love good sound don't use them.
Regards,
Tibi
If you love good sound don't use them.
Regards,
Tibi
Don't expect kemet to tell you that all ceramic caps they make are useless - in audio !
Take a 10nF NPO, connect to an oscilloscope, switch to highest sensitivity and hit that cap. Tell me if you see something on scope.
Regards,
Tibi
Take a 10nF NPO, connect to an oscilloscope, switch to highest sensitivity and hit that cap. Tell me if you see something on scope.
Regards,
Tibi
Unfortunately the only ceramic capacitors I have which I know are NPO are all really small (<100pF) and thus show no response, but I went through several ceramic capacitors from my unsorted box, some of which are almost certainly NPO, and found:tvicol said:
- Some ceramic capacitors (presumably the high-k ones) exhibit huge spikes of 50mV or more when tapped hard.
- Some show only a slight hiccup of maybe a couple of mV.
- All other types of capacitor I tried (polystyrene, polypropylene, polyester) also showed a small bump of around 1mV.
This makes them all look worse than they will be under normal circumstances though, because 'scope probes are very high impedance, and a high-speed finger nail probably exerts a lot of pressure.
EDIT: I just found some 680pF silver mica capacitors. I must have salvaged them from somewhere because I have never bought any. Anyway, I tapped them and got... about 1mV. I wonder if it isn't the case that the ~1mV that all these capacitors are showing isn't coming from somewhere else, because it seems unlikely that they would all be so similar otherwise.
- Status
- Not open for further replies.