Capacitor Questions...

[umcoo]

Hello there,

I have a couple of questions.  How would I know what capacitors are coupling ones on a board layout?  I've read up about them, and know what they do, but can't seem to work out which ones they are?  I'm going off this layout http://gaussmarkov.net/wordpress/circuits/red-llama/   and I think it's C5.

Also, what does the voltage for capacitors mean in stompboxes.  By this, I mean I've seen a cap with the same value, but 3 different ones with various voltages.  Is there a standard stompbox voltage value for caps?  I'm new to this so please excuse my silly questions!

Cheers

[George Giblet]

On that page you can click on the schematic.  On the schematic you can see the coupling caps: C1, C4, C5.

The capacitor voltage is a rating for the capacitor.  Is represents the maximum voltage that should be applied to the capacitor.

Each capacitor in a circuit will have some maximum voltage across it, this will be usually different for each cap.  When you choose caps you have to make sure the capacitor voltage is greater than what the circuit will apply.  You can (usually) use a higher voltage capacitor in place of a lower voltage one in a circuit but not the other way around.  Higher voltage caps are usually larger and more costly, but not always.

A rough guide is if a the power supply for a circuit is x volts then you use caps with voltages greater than x, but be warned, some circuits can apply higher voltages.  (An obvious case is when the circuit boosts the DC voltage rails.)