# Formula for ripple factor in filter circuits

1. Jul 22, 2012

### iampaul

i have come across two different formulas for ripple factor:
One is r= (Vrpp/Vdc), where Vdc is the dc voltage of the output and Vrpp is the peak to peak ripple voltage. My professor uses this formula and I have also seen it being used in basic electronics by Floyd
Another one is r= Vrms/Vdc from electronics by boylestad. Are these correct?

2. Jul 22, 2012

### vk6kro

They are not equivalent but Wikipedia shows them both as being used.

http://en.wikipedia.org/wiki/Ripple_(electrical)

So, it depends on your definition.

Peak to peak is easier to use and RMS would be difficult because the waveform is not sinusoidal.

3. Jul 23, 2012