calculating ripple

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Crow Leader by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla-at-lists.symmetric-dot-net>

How do some people here calculate ripple on a capacitor being charged at
120Hz from a bridge rectifier and a load of x amps? So far every place I've
looked has a different formula, and none have consistent answers.

- the Rado Shack "Building Power Supplies" book suggests

   Vrms = 2.4 I/C

where Vrms = ripple volts
2.4 comes from apparently nowhere
I = current in mA
C = capacitance in uF

- this link on audio amplifier design says
 http://sound.westhost-dot-com/power-supplies.htm#capacitor-value

which comes to a different answer yet again.

- another link has something similar
http://www.mitedu.freeserve.co.uk/Circuits/Power/unreg.htm

- and one more
http://my.integritynet-dot-com.au/purdic/power1.html

and the botton of the page here
http://www.signaltransfer.freeuk-dot-com/powerout.htm

So, what should I use, and where do these strange numbers like the "factor
of 7" for 60Hz and "2.4" come from?

KEN