Hey Guys
Safety Question.
If I charge a 220v capacitor with 5v... Does it accumulate up to 220v or just the voltage I give it? Thanks

A capacitor stores charge, the voltage rating is just the maximum voltage it can have through it without failing

And by failing I mean blowing up

@j4cobgarby Sorry, didn't answer my question...
Does it hold the voltage I provide it with? More? Less?

@GyroGearloose it will hold 5 v

@GyroGearloose again, a capacitor does not store voltage, is stores charge
This charge can be calculated using

Charge = voltage * capacitance

5 Volts applied over a particular amount of time will eventually provide the charge calculated from the above formula

5V to a 220V rated capacitor is perfectly fine, though a waste of money because a lower rated type would be sufficient.

With electrolytic capacitors (among them also Tantalum ones and supercaps / goldcaps), you absolutely have to watch the polarity. These are for DC only, and putting reverse voltage to them will make them explode.

And if you apply variable DC voltage like after rectification of AC using some diodes, you need to check that they can take the ripple. They have an internal resistence ("ESR"), and charging/discharging them makes them warm because of that ESR. That's why "low ESR" types are nice, except if your application requires some dampening against ringing - some voltage regulators list "no ESR" in their application notes.

Well, I'm salvaging old boards, and I have a industrial grade valve controler board with lots of good quality stuff.
Btw this ones are 50V and 30V
Btw, the formula is in uFs?

Like, Capacitor 50V 1000uF
V = 5v x 1000 (s)?

The voltage will be just the one you have put to the capacitor, in your case 5V. What depends on the capacity is how much charge this is, i.e. how many electrons. A bigger capacitor stores more charge at the same voltage. It takes longer to charge, and longer to discharge.

Ok, I think I get it, It holds a maximum of given voltage, the rest is charge like in a battery... So If I give 5V it only discharges 5V, If I give 12V it only discharges 12V...

@GyroGearloose yeah, but with a catch. Say you have charged the capacitor to 5V and take off the charging voltage. It's still 5V, just like a charged battery. But now, if you discharge it to feed some circuit, the voltage will go down. How quickly, that depends on how much current you draw and how big the capacity is:

https://electronics-tutorials.ws/rc...

@Fast-Nop Thanks for the link.
Nah It's mostly for fun now, make leds fade without an MCU and such.
I'm planning some ideas for Halloween and x-mas and for lights might be a good add-on in some cases (like lightning effect for Halloween)

It is going to charge to 5V

Capacitors arent magic. They are like buckiets - if you put only 5% of the max you are going to get 5%.

That voltage is the max one before you get fireworks instead.

@Gregozor2121 Thanks, exactly the answer I needed for my confidence.
The percentage made me understand it.
:D