another newbee question re: caps (math)

I'm confused about this. Am I correct that:

resistors in parallel will divide the resistance, and voltage will be the sum of the resistors.

capacitors in parallel will be the sum of the capacitance, but voltage will be equal to the lowest rated cap?

Thanks,
Joel

[quote author="Mbira"]resistors in parallel will divide the resistance, and voltage will be the sum of the resistors.[/quote]
The voltage will be the same accross all the resistors. But since you normally don't have to worry about voltage ratings, why worry?

capacitors in parallel will be the sum of the capacitance, but voltage will be equal to the lowest rated cap?

Click to expand...

The voltage will be the same accross all the caps. But you should keep the voltage lower than the rating of lowest-rated cap.

Best regards,

Mikkel C. Simonsen

OK, so that means caps wired in parallel will not increase the voltage capability of those two caps by splitting the power going to each cap?

Joel

[quote author="Mbira"]OK, so that means caps wired in parallel will not increase the voltage capability of those two caps by splitting the power going to each cap?[/quote]
Correct. caps wired in series will increase the total voltage rating by sharing the voltage between the caps,but in parallel, each cap sees the full viltage and gets the full brunt. Only current is shared in that instance, not voltage.

resistors in parallel will divide the resistance, and voltage will be the sum of the resistors.

Click to expand...

Yes and No... resistors in parallel will divide the resistance, and the total wattage will be increased, though not necessarily by the sum of the resistors' wattages. -Depends on which is the 'weakest link'.

Keith

Thanks guys-
I'm trying to figure out how to have some power supply caps rated (220uf at 350V) without having to go buy some...I guess I'll just order them. Thanks again!
Joel

caps wired in series will increase the total voltage rating by sharing the voltage between the caps,

Click to expand...

I'm trying to figure out how to have some power supply caps rated (220uf at 350V) without having to go buy some...

Click to expand...

When you`re putting caps in series to make up voltage rating in an HT supply for valves it is a good idea to put a high value resistor (maybe 220K)in parallel with each capacitor. This means that if one of the caps goes short or leaky then you don`t get the full HT voltage across the other one, which would be to much for it. Make sure the resistors are the same value so that the voltage is equal across each cap. This is also safe because you have bleeder resistors, which will discharge the smoothing caps when you power off, which may remain charged up if you have some sort of fault occur.

Damn, guys...sorry I'm not getting this. What is the equation to figure out voltage for caps in series and parallel?

Wait never mind:

http://www.oz.net/~coilgun/theory/capacitors2.htm

This has helped explain things to me. I'll put this in the equation thread so folks can see it...

Thanks again.
Joel