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capacitor in aprallel

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dann11

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why do we usually connect capacitor in parallel? thanks
 

If we connect the capacitor in parallel combination then the capacitance of the the capacitor is added i.e similar to the the resistor connected in series combination.
 

Not always in parallel. You can connect them in series when the voltages exceed the breakdown voltage of a single capacitor.
 

Also depends on what you are trying to achieve.
Basically you need to consider the impedance of each capacitor which is related to the frequency of the voltage across it. For a capacitor the impedance is "Z=1/jwC" where w is related to the frequency and C is the capacitance.
For example, you might have a (relatively) large electrolytic capacitor across the supply lines of a circuit to help smooth out supply variations due to varying current draw on the power supply (or whatever). Having a large C means that it will have a small(ish) impedance to lower frequencies but will be relatively ineffective at higher frequencies.
You might also have a (relatively) small capacitor in parallel to it to by-pass high frequency noise that can be induced in the supply from some source. The small C will mean the impedance will be high at lower frequency but will drop as the frequency increases.
Susan
 

In most of the circuit that I used, I see that the capacitor is connected in parallel with the other component like inductor and resistors.
The capacitor is used to hold the charge for some time and when maximum charge is stored them it allow to flow the charge.So it depends on the circuit where you use and for what purpose you are using the capacitor.
 

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Aussie Susan said:
Also depends on what you are trying to achieve.
Basically you need to consider the impedance of each capacitor which is related to the frequency of the voltage across it. For a capacitor the impedance is "Z=1/jwC" where w is related to the frequency and C is the capacitance.
For example, you might have a (relatively) large electrolytic capacitor across the supply lines of a circuit to help smooth out supply variations due to varying current draw on the power supply (or whatever). Having a large C means that it will have a small(ish) impedance to lower frequencies but will be relatively ineffective at higher frequencies.
You might also have a (relatively) small capacitor in parallel to it to by-pass high frequency noise that can be induced in the supply from some source. The small C will mean the impedance will be high at lower frequency but will drop as the frequency increases.
Susan
Click to expand...

Is it really important to consider the impedance value of the capacitor?.. Like, if i will really used it just to compensate on the current variation..
 

Hi,

You don't tell much details, instead you ask very general questions.

But every circuit us different.

Are you talking about huge bulk capacitors for mains frequency application, or small capacitors fir frequency generation, or thousands of applications inbetween?

Is it really important to consider the impedance value of the capacitor?.. Like, if i will really used it just to compensate on the current variation..
Click to expand...
I'd say: yes.
But often this is already done in datasheets and application notes, and they tell you what capacitor to use.

Or you build similar circuits, then from the experience of the first circuits you know how to handle the next ones.

With some circuits there is a rule of thumb, and sometimes you use it without knowing it is the "impedance" calculation.

****
If you need more information, then please post a specific schematic, to talk about.

Klaus
 

dann11 said:
Is it really important to consider the impedance value of the capacitor?.. Like, if i will really used it just to compensate on the current variation..
Click to expand...

It can be for two reasons. Physical implementations of a capacitor are made with imperfect metal, and occupy actual space. This gives rise to parasitic resistance and parasitic inductance.

The parasitic resistance realistically means heating of the device. Overheating the device could destroy it.

The parasitic inductance means at high frequencies the device no longer acts as a capacitor. For digital logic IC's, this can be an issue as these IC's can draw current in small spikes millions of times per second.
 

santoshaxl said:
its a charge bank .why do we open account in many banks ?
Click to expand...

you put money in many banks , because there is a limit on the money that you can put in each bank.

here , instead of ' bank' use ' capacitor' and money with charge .

what is the value of each capacitor , in your bank :roll:?( or written on each cap ?)
 

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