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# How to charge up a capacitor? Answered

hi,

i am new ,  i want to know How to charge up a capacitor?

i have a 10v capacitor when i link it to 1.5v or 9v its only charge 1.5 or 9v and no more

how i can charge it full ?

thank you

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## Discussions

Well, I think the answer is obvious.

When you connect a capacitor to a 1.5 volt source, it charges to 1.5 volts.

When you connect a capacitor to a 9.0 volt source, it charges to 9.0 volts.

If you sort of generalize from what you have observed, then you might expect...

When you connect a capacitor to a Y volt source, it charges to Y volts, where Y is any real number.

To say it another way: When you connect a capacitor to a constant voltage source, the capacitor (eventually) charges to the same voltage as the source.

By the way, in practice you DO NOT charge a capacitor to a voltage greater than, or exactly equal to, its voltage rating. I mean, not unless you're intentionally trying to break the capacitor.

So essentially, 9 volts is close enough to "full", for a 10 volt capacitor. You know, charge a 10 volt cap to 9 volts, and that's good enough. You're done. Declare victory! Move on to the next challenge.

By the way, there exist circuits which can be powered by a small battery, e.g. 1.5 or 3.0 volts, yet charge a capacitor to a voltage much higher than the battery voltage. For example the circuit for charging a camera flash can charge its capacitor to approximately 300 volts. However, doing this requires some voodoo. It is more complicated than simply connecting the battery and capacitor together.

If you interested specifically in camera flash capacitor charging circuits, this page,
http://www.talkingelectronics.com/projects/XenonFl...

does a good job of explaining how these work.

Check Wikipedia for capicitors.
There are also lots of electronics websites showing simple circuits and explaining how the work - a good point to start if you want to understand electronics.

You need a supply equal to BUT NOT exceeding the capacitors voltage.

You can't get something for nothing.

The highest voltage you will attain is 10 volts. If you try to charge it with a higher voltage the capacitor may well explode.