Capacitors

How come capactors are used so much in electronics for exampel: http://www.instructables.com/id/Portable-USB-Charger-Version-2.0/ what are those 2 capacitor doing?

Comments

[steveastrouk]

They're reservoir and filtering capacitors. One filters low frequency noise, the other high.

[Balls of Kevlar]

Thanks, but how do I know where to use capacitors, and how do I know how big a value I need.

[steveastrouk]

That's where you have to learn about them. I can't hope to condense the knowledge you need into a reply on Instructables.

Capacitors are used as an integral part of filter circuits, timing circuits and power supplies -different rules and types apply, but all are fundamentally driven by the fact that the impedance of a capacitor causes a phase lag between the flow of current and the build up of voltage, and also to an impedance that decreases as frequency increases.

Do you know anything yet about AC circuits and circuit theory ? Start from that.

Steve

[Balls of Kevlar]

Thanks, but I my question is more "how do I kmow when and where there is noise in my circuits

SKC

[steveastrouk]

You design with the assumption there will be noise, and stop it happening. It is always important to design noise out, rather than to react to its presence.

I don't know what your level of knowledge is. You sound like you need to get some solid theory on board.