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### Topic: The capcitor (Read 1 time)previous topic - next topic

#### nik993

##### Mar 02, 2011, 05:08 pm
What does it do?

i understand that it stores energy and discharges it when filled completely, but why would you use it? what does it do for you in a circuit? what simple uses does it have?

#### biocow

#1
##### Mar 02, 2011, 05:33 pm
Capacitors also take time to fill up and discharge. This can act like a cushion in your circuit.

A circuit without a cap is like slamming on the gas pedal of a drag racer. 0 - 100mph in a few seconds.

Add a Cap and resistor and it's like slowly stepping on the gas of a Cadilac. You'll get to 100mph eventually, it'll just take 15 or 20 seconds.

And just the opposite. No cap = slamming into a brick wall. With a cap = slowing from 100 to 0 over 30 seconds.

I'm sure others will have better examples and similes.

#### MarkT

#2
##### Mar 02, 2011, 06:42 pm
The deep answer is that capacitors have state.

More practically capacitors allow filtering, store values as charge or voltage, decouple, couple, store energy, integrate a current...  There's so much they are used for its amazing!

Have a look in the learning section for circuits with capacitors - the commonest use is decoupling in a microcontroller, but in analog circuits everything uses capacitors.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

#### Grumpy_Mike

#3
##### Mar 02, 2011, 06:59 pm
A capacitor is a frequency dependent resistor for AC.

Therefore it can be used to short out high frequencies and let low ones through if you put it across a signal, or the other way round if you put it in line with the signal.
Quote
the commonest use is decoupling

http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html

#### westfw

#4
##### Mar 03, 2011, 01:16 am
Capacitors do calculus!

http://arduino.cc/forum/index.php/topic,52838.0.html

#### nik993

#5
##### Mar 03, 2011, 04:34 pm
wow, thanks you guys... i guess i have to study up alot more than i thought! =)

#### Grumpy_Mike

#6
##### Mar 03, 2011, 04:39 pm
Just another point:-

Quote
i understand that it stores energy and discharges it when filled completely,

No that's not how it works. It will only discharge when is is placed across a load or sees a voltage lower that it has charged to.
If it worked like you thought it would be an oscillator all by itself.

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