Harry Muscle said:
What kind of cap and what value should I use to smooth out the DC
before I feed it to the regulator (LM 340T12)? Is there a formula for this
cap value? Is anything else required?
The "finger-in-air" figure I have used for many years is "2000uF per amp".
So, if you need only 100mA, use 200uF, and then put it into your regulator.
Remember to rate the voltage high-enough (eg 24v ac transformer often gives
about 30v under low load, multiply by 1.4 (if using full bridge rectifier)
so I'd select 50V working).