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¿What is the difference among capacitors?

C

chriswilliams

Jan 1, 1970
0
As it is known there are different types of capacitors:
*Electrolyitic
*Tantalum
*Ceramic

But ¿which is the difference among them.?

It wanted to know if they can be substituted among them,
that is to say if I can substitute one ceramic by
one electrolytic or an electrolytic for one of tantalum.

Thanks in advance for any comment.
 
A

Andrew Holme

Jan 1, 1970
0
chriswilliams said:
As it is known there are different types of capacitors:
*Electrolyitic
*Tantalum
*Ceramic

But ¿which is the difference among them.?

Capacitance value for one thing. Ceramics cover from 1pF up to just short
of 1uF. Then, there's some overlap as electrolytics and tants take over for
larger values. Tants tend to be physically smaller than electrolytics for
the same capacitance / voltage rating. For really large values,
electrolytics are your only choice.

Another difference: ceramics are not polarity sensitive.

Those three are not the only types: there's polystyrene, polyester layer,
monolithic ceramic .... each offering different performance in terms of
precision, temperature stability, physical size, voltage rating,
self-resonant frequency ....
It wanted to know if they can be substituted among them,
that is to say if I can substitute one ceramic by
one electrolytic or an electrolytic for one of tantalum.

If the capacitance and rated voltage match, it may be possible to substitute
an electrolytic for a tant, or vice-versa.
 
J

John Popelish

Jan 1, 1970
0
chriswilliams said:
As it is known there are different types of capacitors:
*Electrolyitic
*Tantalum
*Ceramic

But ¿which is the difference among them.?

It wanted to know if they can be substituted among them,
that is to say if I can substitute one ceramic by
one electrolytic or an electrolytic for one of tantalum.

Thanks in advance for any comment.

Here is a good place to start:
http://my.execpc.com/~endlr/index.html
 
I saw those 6w FL dc driver circuit was useing tantalum cap instead of
cheap ceramic cap, reason was unknow, may be due to the driver's
frequency and ceramic can't handle such high frequency ?
 
P

PeteS

Jan 1, 1970
0
Andrew said:
Capacitance value for one thing. Ceramics cover from 1pF up to just short
of 1uF. Then, there's some overlap as electrolytics and tants take over for
larger values. Tants tend to be physically smaller than electrolytics for
the same capacitance / voltage rating. For really large values,
electrolytics are your only choice.

Another difference: ceramics are not polarity sensitive.

Those three are not the only types: there's polystyrene, polyester layer,
monolithic ceramic .... each offering different performance in terms of
precision, temperature stability, physical size, voltage rating,
self-resonant frequency ....


If the capacitance and rated voltage match, it may be possible to substitute
an electrolytic for a tant, or vice-versa.

Minor nit - I use 100uF ceramics (Panasonic). Not suitable at anything
approaching a high voltage, but great below 5V.

Whether devices can be substituted depends where it is used. All caps
have other specifications, such as ESR (equivalent series resistance),
ESL (Equivalent series inductance), leakage, ripple performance, surge
performance, rms current handling and a host of other variations due to
environmental conditions as well as the ones listed by Andrew.

In feedback loops esr, in particular, becomes a critical issue. See for
instance, the datasheet linked here:
http://www.national.com/pf/LP/LP3961.html

In the application hints, you'll find the output esr and input C - esr
are considered (and important for loop stability).

The other characteristics of the various types of cap can become issues
in other circuits.

Another quick example: tantalums have relatively poor surge performance
(they can become spectacularly pyrotechnic), so choosing one where such
a surge may exist is not as simple as looking at rms handling and
capacitance.

So the answer is not a simple yes or no - as always in engineering 'It
Depends'

Cheers

PeteS
 
P

PeteS

Jan 1, 1970
0
chriswilliams said:
As it is known there are different types of capacitors:
*Electrolyitic
*Tantalum
*Ceramic


There are more than that

A few that come to mind:

Polystyrene
Mica
Mylar
Air (used to see them in old radio sets)
Oil (really! I've used them)
Polyester
Polyphenylene sulphide
Polypropylene
Niobium Oxide
Polymer tantalum (a variation on a theme)
Then there are things like the Sanyo TPA POSCAP (Solid electrolytic,
sintered tantalum anode, Polymerised organic semiconductor electrolyte)

Ceramics themselves have some variety
Disc and plate
Multilayer
(I am sure the crowd will join in and add things I have forgotten to
add or simply not come across)

Each has their pros and cons - Mylar for instance, has superb
dielectric characteristics across temperature amongst other things.

Cheers

PeteS
 
J

Jasen Betts

Jan 1, 1970
0
As it is known there are different types of capacitors:
*Electrolyitic
*Tantalum
*Ceramic

But ¿which is the difference among them.?

It wanted to know if they can be substituted among them,
that is to say if I can substitute one ceramic by
one electrolytic or an electrolytic for one of tantalum.

Thanks in advance for any comment.


ceramic: low incuctance, low resistance, suited to radio frequency work.
tantalum low-ish resistance, compact, high-ish capacity
electrolytic, moderate resistance, large capacity, cheap.

for filtering often a ceramic is paired with a tantalum or electrolytic.
the ceramin deals with the sharp spikes and the other one absorbes the
blunter surges.
 
J

Jasen Betts

Jan 1, 1970
0
There are more than that

A few that come to mind:

Polystyrene
Mica
Mylar
Air (used to see them in old radio sets)
Oil (really! I've used them)
Polyester
Polyphenylene sulphide
Polypropylene
Niobium Oxide
Polymer tantalum (a variation on a theme)
Then there are things like the Sanyo TPA POSCAP (Solid electrolytic,
sintered tantalum anode, Polymerised organic semiconductor electrolyte)

Ceramics themselves have some variety
Disc and plate
Multilayer
(I am sure the crowd will join in and add things I have forgotten to
add or simply not come across)

waxed paper often used alongside air and mica caps. (obsolete)

glass (leyden jars used in some home-made tesla coils
and the back half of a CRT)

I've also seen some with bitumin (I think) in them used for powerfactor
correction (PFC) in some old fluorescent lights.



Bye.
Jasen
 
P

Paul Burridge

Jan 1, 1970
0
Each has their pros and cons - Mylar for instance, has superb
dielectric characteristics across temperature amongst other things.

Mebe. But mylars have huge amounts of parasitic inductance, making
them pretty hopeless for RF applications. As someone else said, the
choice of capacitor type is governed by the intended application.
 
P

Paul Burridge

Jan 1, 1970
0
for filtering often a ceramic is paired with a tantalum or electrolytic.
the ceramin deals with the sharp spikes and the other one absorbes the
blunter surges.

Good point. This often confuses a lot of folks. They see a 100nF in
parallel with a 4.7u and can't understand why the design doesn't
simply specify one capacitor of equivalent value. This example
illustrates that cap choice often goes way beyond just the desired
value.
 
D

Deefoo

Jan 1, 1970
0
Paul Burridge said:
Good point. This often confuses a lot of folks. They see a 100nF in
parallel with a 4.7u and can't understand why the design doesn't
simply specify one capacitor of equivalent value. This example

Because 4.8u caps are hard to find ;)

--DF
 
P

PeteS

Jan 1, 1970
0
Paul said:
Good point. This often confuses a lot of folks. They see a 100nF in
parallel with a 4.7u and can't understand why the design doesn't
simply specify one capacitor of equivalent value. This example
illustrates that cap choice often goes way beyond just the desired
value.

I have designs that are 100% ceramic, as far as the caps go (Not all
designs, but there are times it can work). Makes the power supply loop
a little difficult to compensate, but definitely worth the effort. Even
so, I agree on the confusion - and I still bypass my 100uF ceramics
with a 0.1/0.01uF on occasion. Most cap mfrs now now give Z vs. F
curves for each cap (although you may need to dig that out of their web
sites) which can make life somewhat easier.

Artificial intelligence is no match for natural stupidity

Cheers

PeteS
 
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