DC CAPACITOR

[domnic]

How does a dc capacitor differ from a ac capacitor from a electrical stand point. and how they are made.

 

[ggunn]

How does a dc capacitor differ from a ac capacitor from a electrical stand point. and how they are made.

A capacitor is a capacitor. There is no DC versus AC capacitor, and caps don't do much in a pure DC circuit.

 

[gar]

171116-2021 EST

I believe you would like a simple answer.

What can be described as an ordinary capacitor will consist of two conductive plates separated by air or some other dielectric material.

The dielectric constant of the insulating material and other parameters determines the capacitance of the capacitor.

This type of capacitor is bipolar. That is it is not sensitive to what polarity is applied.

The dielectric material is usually quite thin, in the 1/1000" range.

These capacitors can be used in either AC or DC applications.


An electrolytic capacitor in its simplest form can only operate with one polarity of applied voltage or the oxide layer that provides the dielectric will be destroyed. This can operate with a DC bias plus a superimposed AC signal so long as the voltage never reverses.


There are special AC electrolytic capacitors that are really back to back DC capacitors.


For detailed information see various references, one of which is: https://en.wikipedia.org/wiki/Electrolytic_capacitor

.

 

[gar]

171116-2046 EST

ggunn:

You need to clarify your statement.

.

 

[junkhound]

A capacitor is a capacitor. There is no DC versus AC capacitor, and caps don't do much in a pure DC circuit.

Quite a huge difference in how ac and dc caps are made. Try using a 200 Vdc rated cap on a 120vac line and see how long it lasts.

Start with electrolytics. For ac, one needs to put 2 in series back to back as electrolytics are polarized.

Move on to other caps. Lifetime of the dielectric varies enormously by material type and whether used on dc or ac. ESR, ripple capability, etc. etc. vary a lot.

Very large subject and many technology details such as terminations, frequency response (self resonance), temperature, etc......

 

[Besoeker]

A capacitor is a capacitor. There is no DC versus AC capacitor,

There is. Stick an electrolytic in wrong polarity and you will get a dramatic demonstration..............

 

[ggunn]

171116-2046 EST

ggunn:

You need to clarify your statement.

.

Actually, I don't. Others have shown that there is a difference when in comes to electrolytics. I stand corrected in that case.