Power Converter 220V ac to 12V dc

A friend required an AC to DC converter to power a light circuit for a water fountain.
I have decided to design a circuit on his behalf.

Below is the required circuit diagram. I couldn't scan it because we currently experiencing high voltage electricity in my area; my bulbs and my scanner power adapter are gone; thus you have to manage a snap shot from my phone.

I hope this picture is clear enough.

Let me explain the circuit.

First, the 220V AC is stepped down to 12V AC using a transformer of appropriate wattage, the 12 V AC is rectified to DC using a bridge rectifier of appropriate wattage. Note, the DC voltage has ripples and these ripples have a low of 0V and a peak 16.97V - swinging from 0V to 16.97V.

A capacitor is connected in parallel to make the DC voltage eliminate ripples and the resistor across the capacitor is called the bleeding resistor. The capacitor should eliminate about 80% of the ripples. The resistor is used to discharge the capacitor whenever the the circuit is not powered up. Contact me for the calculation on values of the capacitor and resistor.

The voltage regulator 7812 is used to flatten the DC circuit completely on 12V. Since, it comes in different capacity; thus, I recommend that you use as many as possible in parallel to achieve the desired power requirement.

If you would like to have these lights switched ON and OFF automatically, don't hesitate to post comments below - it will come with a price though; we are all entrepreneurs.