Answer 1—The peak output voltage of the transformer is 14.14 V. 2 × 0.7 V = 1.4 V is dropped in the bridge rectifier, so the peak voltage on the capacitor is about 12.7 V.

The regulator has a minimum input voltage requirement of 8.0 V; therefore, you can allow a maximum of about 4 V of ripple on the capacitor.

With a bridge rectifier and a 60-Hz line frequency, the capacitor gets charged 120 times each second, or every 8.33 ms.

The following formula is for sizing filter capacitors:  

Plugging in the above numbers gives a result of about 2,000 µF.

Contributor: David Tweed