Capacitor voltage rating conversion

[alexg]

I have searched on the net and have not found the answer.

How do I convert VAC capacitor voltage rating into VDC rating?

Thanks.

[torrence]

AC voltage ratings are given as the RMS of a sinusoidal
signal, so the peak-to-peak voltage values will be sqrt(2)
larger than the RMS. In principle, a capacitor rated at
100 volts AC should then be able to handle 140 volts DC.
Note that the amount of time that an AC voltage is near
its peak voltage is quite small, so the probability of breakdown
for a DC voltage near this rated value may go up significantly.
It is always a good idea to leave as much safety margin
as practical, and design your circuit so that a single component
failure isn't catastrophic.

[alexg]

Thanks.

Some people told me DC voltage rating of caps is 1.4X the AC rating, some said it is 2X.

Your explanation made a lot of sense. Thanks.

[lineup]

It is most often, when possible,
best to have capacitors well higher rated than you actually will need.

This means bigger capacitors.

Bigger capacitors = higher nominal voltage,
have some better electrical quality performance parameters.

This goes for almost every audio use of any capacitor.

Another thing is of course if you can get bigger capacitors somewhere.
This is not always the case.
And then we have how much money you are willing to spend.


But generally speaking, capacitors are not the main cost of your amplifier.
So put this into the perspective of:
- Chassis cost
- Transformers cost
... and you will find that you will be able to get real super class capacitors
before reaching even a small percent of the other costs in your amplifier.

Regards Lineup