The voltage doesn't affect the capacitance in any way.
Quote from: majenko on Aug 18, 2012, 11:28 pmThe voltage doesn't affect the capacitance in any way.Well, for ceramic capacitors voltage does matter. Ceramics (excluding C0G/NPO) have a voltage (and temp) coefficient associated with them. The closer the applied voltage is to the rated voltage, the less effective capacitance you get. For cheap dielectrics like Y5V and Z5U the loss can be as high as 60%.
Good working practice is to use a voltage rating of at least twice the expected voltage. More is better.
Yes, but we're not talking ceramics here - we're talking electrolytics.
Quote from: RoyK on Aug 18, 2012, 04:44 pmGood working practice is to use a voltage rating of at least twice the expected voltage. More is better.Working voltage is not the same as an "absolute maximum rating". Semiconductor datasheets often highlight the abs max ratings rather than recommended working conditions. Capacitor datasheets are more sensible. Choose a working voltage greater than the maximum actual in-circuit voltage it will be exposed to, factor of two is unnecessary. The device is spec'd to run at working voltage continuously. Higher voltages upto the "surge voltage" rating are tolerable for brief periods (but may lead to greater leakage current).
Quote from: majenko on Aug 18, 2012, 11:49 pmYes, but we're not talking ceramics here - we're talking electrolytics.The capacitor type was never mentioned in this thread. Which is a dangerous when talking about capacitors because different dielectrics have different behaviors and guidelines.(You already deleted the comment, so I assume you realize 100uF ceramics do exist.)