Beginner question about capasitors

[GeirA]

A friend gave me his Arduino starter kit, and I have had a lot of fun building different things on a breadboard.

So my interest in electronics is a fact. But I soon undestood that my total lack of knowledge in basic electronics prevents me from building something on my own. So I got myself some books, and are slowly getting some more knowledge.

Now I'm learning about capasitors. I understand how to charge and discharge a capasitor, but I don't understand what their purpose is. They are on nearly every schematics I've seen - but I can't figure out what they do.

Can someone please tell me a bit about what their purpose is?

Thanks!

 

[audioguru]

A capacitor can filter a DC voltage so it is smooth.
A capacitor can pass low frequencies but reduce high frequencies.
A capacitor can pass high frequencies but reduce low frequencies.
A capacitor can block a DC voltage but pass an AC signal.
A capacitor can change an abrupt on-off signal to a smooth slow ramp up then slow ramp down signal to slowly brighten and fade an LED light.
A capacitor can be combined with an inductor to make a resonant circuit.

 

[Reloadron]

There is no single simple answer to your question. Real simple is a capacitor opposes a voltage change, moving right along to:

A capacitor (formerly known as condenser) is a passive electronic component consisting of a pair of conductors separated by a dielectric (insulator). When there is a potential difference (voltage) across the conductors a static electric field develops in the dielectric that stores energy and produces a mechanical force between the conductors. An ideal capacitor is characterized by a single constant value, capacitance, measured in farads. This is the ratio of the electric charge on each conductor to the potential difference between them.

Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass, in filter networks, for smoothing the output of power supplies, in the resonant circuits that tune radios to particular frequencies and for many other purposes.

The effect is greatest when there is a narrow separation between large areas of conductor, hence capacitor conductors are often called "plates", referring to an early means of construction. In practice the dielectric between the plates passes a small amount of leakage current and also has an electric field strength limit, resulting in a breakdown voltage, while the conductors and leads introduce an equivalent series resistance.

With the above quiote stolen from here. Some of what you ask in what seems a simple question can take years to really understand.

Ron

 

[GeirA]

Thanks a lot!

I have put the Arduino aside, and will work more with basic electronics - and hope I will get into things with a bit of practise.