Well from i can see here D1 is just for protection in case someone would ever reverse the polarity's, and the 10 ohm in front is soften the blow of the D1. I'm guessing the 47uF cap is to block some ac, i was going to use a 50k var to get a more precise 3:1 ratio, The D3 and D4 is for protecting my pic for reverse polarity's also. If this is all correct, i just can't see what all those extra capacitors do.

looking forward to your explanation