hi guys

I have problem when I wanted design DC power supply

( I used

**)**

*center tap full wave rectifier with smooth capacitor and zener diode*that problem is how I can determine

**ripple voltage**to

**find capacitor value**?

I have following values

- output voltage = 4.7 V

- input voltage from transformer = 9 V . "

**Is it peak or RMS value ?**"

-load resistance = 100 Ω.

- frequency = 60 Hz .

I asked my friend , he told me you can assume it (

**ripple voltage )**

but how I can assume it ?? is there certain range for assumption ??