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### Topic: use of capacitor (Read 987 times)previous topic - next topic

#### A4kash

##### Jan 06, 2013, 05:28 am
If capacitor blocks dc then why it is actually used in the circuit?

#### larryd

#1
##### Jan 06, 2013, 05:40 am
A good place to find out:
http://www.electronics-tutorials.ws/capacitor/cap_1.html
No technical PMs.
The last thing you did is where you should start looking.

#### retrolefty

#2
##### Jan 06, 2013, 05:45 am

If capacitor blocks dc then why it is actually used in the circuit?

Being able to pass AC voltages but block DC voltages is a very useful feature. Audio amplifiers are made up of individual stages of amplification, preamp stage, power amp stage, etc. It's very useful to be able to pass the ac audio signal from one stage to the next using a series 'coupling' capacitor, without upsetting or having to deal with the individual different DC bias voltages that each stage uses. A bypass cap from a DC power rail to ground allows AC noise voltages to pass to ground without shorting out the DC bus to ground.

Lefty

#### cmiyc

#3
##### Jan 06, 2013, 09:41 am

If capacitor blocks dc then why it is actually used in the circuit?

What circuit?

The primary use of a capacitor is to use to store charge.  Blocking DC is just one of the uses.
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

#### A4kash

#4
##### Jan 06, 2013, 03:36 pm

If capacitor blocks dc then why it is actually used in the circuit?

What circuit?

The primary use of a capacitor is to use to store charge.  Blocking DC is just one of the uses.

IT blocks DC doesn't it mean that no current will flow through it?

#### Docedison

#5
##### Jan 06, 2013, 04:10 pm
Yes, Direct Current. A capacitor will pass Alternating Current, Not Direct Currnet, Which is what Lefty was talking about.

Bob
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

#### MarkT

#6
##### Jan 06, 2013, 11:11 pm
A circuit with only DC isn't very interesting!
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