Need Some Help About Capacitors.

[psrkallez06]

So, i have tried to read as much as i can about capacitors, but there are still some things that i don't understand. For example, Let's say that i have a 12v power supply, and before the output i put a 300 volts capacitor, does that mean that my output will be 300v? :S = stuff blows up haha. I hope that you understand what i mean.

How does the voltage concept work for capacitors?

Thanks!

 

[bluetobits]

The voltage rating on a capacitor is the maximum amount that it can be safely exposed to

 

[ProDave]

.... So it will make no difference, your output will still be 12V

 

[Lurch]

.... So it will make no difference, your output will still be 12V

Not necessarily. Your power supply output will be higher than the raw voltage after you put the cap across the output.

 

[Sidewinder]

Only by the "peak ripple" as it were.

 

[Lurch]

I was going to start the theory behind RMS and p-p but I am trying to do 3 things at once and it wasn't making much sense so deleted that part!

 

[Doc Hudson]

So, i have tried to read as much as i can about capacitors, but there are still some things that i don't understand. For example, Let's say that i have a 12v power supply, and before the output i put a 300 volts capacitor, does that mean that my output will be 300v? :S = stuff blows up haha. I hope that you understand what i mean.

How does the voltage concept work for capacitors?

Thanks!

Another illustration that may help is that a capacitor only stores a voltage it doesn't generate any voltage. The voltage rating is the maximum amount it is designed to work with without it failing.  Consider if I had a 2 Gallon bucket, that can store up to 2 gallons maximum.  But if I just want to store half a gallon the bucket can retain my half gallon quite safely, but if I wanted to try and store 3 gallons in my 2 gallon bucket there is going to be a failure. Every electronic component, switches, wires, resistors, light bulbs etc, have maximum voltages they are designed to work up to, You can generally use a higher rated device for a lower rated application but not vice-versa,  

Doc H.

 

[Lurch]

That analogy doesn't hold water (pun intended) as the "3 gallons in a 2 gallon bucket" thing is more about the inductance and your analogy seems to be answering the OP which was about voltage.

 

[psrkallez06]

Thanks for all the answers! I think i get this a little bit more hehe, One more question. Like you said that it only stores voltages and not generates any, How come some components has low capacitors? I mean, even if you building a power supply that will generate 5 volts, why use (for example) a 20 volts capacitor when you can use a 400 volts one = less chance for it to fail because it's gonna take a LOT for it to be (over volted)? I understand that a 400v cap is usually a lot bigger than a 25v one (depands on the uF of course) but still hehe.

 

[ProDave]

Becasue a 400V capacitor will cost more and be a LOT bigger in physical size, so you only fit what's needed.

Capacitors fail regularly these days not because they are over run, but because most of them are made with rubbish materials.

 

[psrkallez06]

Got it! Thanks everyone

 

[rubygilmore]

The capacitor's voltage rating is the maximum amount of voltage that the capacitor can exposed to and store safely. The most important thing you should know about capacitors is that capacitors store X charge at X voltage. Which means, they hold a certain size charge (1µF, 100µF, 1000µF, etc.) at a specified voltage (10V, 25V, 50V, etc.).