edit: Looks like I'm not suppost to post in this forum, sorry. Cant figure out how to delete or move the post.

Ok so I've built up a few electronic kits , played with microcontrollers and digital circuts, but my basic understanding of electronic components is lacking. I have read a lot of stuff on this but I'm a little dense.

Here's my questions.

Does the voltage of a cap matter that much? Can I 'fill up' a 16volt with 2 volts? or will the capacitor top out and stop taking charge at 2 volts?

OR, does the voltage listed for the capacitor instead represent the voltage at which it will discharge? Or am I just completely confused all together??

I'm trying to understand solar engines for beam robotics, and super caps for LED flashlights. any simple english for dummies type reply is greatly appreciated.

 

Yes, if you put a voltage across the capacitor which is greater than the rated voltage written on the side of the capacitor, the capacitor will be damaged. At the worst it will go BANG!!

If you charge up a capacitor to 2 volts, you have a capacitor which is charged to 2 volts. It will not magically give 16 volts.

Yes you are confused!
When you discharge the capacitor which we just charged from a 2 volt supply, the voltage from the capacitor will start at 2volts and drop exponentially to 0 volts (not mathematically correct, but this is the very simplified description).

JimB

__________________
Experience is directly proportional to the value of the equipment ruined.

 

Now I'm confused too. Why would the voltage not drop exponentially?

__________________
L.Chung

 

Yes the voltage drops exponentially.
But, mathematically it never reaches zero.
Practically, yes it does reach zero, as near as makes no difference.

JimB

__________________
Experience is directly proportional to the value of the equipment ruined.

 

Yeah, a 450v rated capacitor I took from my old monitor which had been left for about 6 months (so it must be fully discharged) was found to have 4mV or so in it. But for any sensible application this doesn't matter.

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Angry!? I'm absolutely electrolytic!

Will have to make do with myspace now I guess...

 

The final anode and aquadag of a CRT form the two plates of a capacitor, and these can stay charged for years!!

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

Cool, I wasn't as confused as I thought I was. So here's another question. How do you go about filling up a high voltage capacitor with a small 1.5 volt battery? Like a flash in a camera does?

 

Normally its done with a small inverter transformer and possibly a voltage multiplier . I would recommend looking into basic tutorials on transformers and that should hopefully help you out.

 

Thanks, i'll read up on them.

 

A cap blocks DC and passes AC.

 

There are a couple of other things to consider. For example if the capacitor is charged with a constant current source the voltage across the capacitor will rise at a linear rate and not exponentially. On the same hand if the
capacitor is discharged by a constant current load the voltage will also decrease at linear rate.

The true diffination of the function of a capacitor is a device that opposes the change of voltage across it. So it charges and discharges to maintain
the voltage.

__________________
The great thing about electronics is unlimited ways to do the job. The only limit is one\'s imagination. I generally think my way is best.
Show me a different way. I have an open mind.

 

If I recall correctly:

"capacitance is the property of a circuit to store energy in the form of an electrostatic field"

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk