Friends at don’t like large-sized of a transformer. I begs for to advise 15VDC regulator power supply can give the trend current get low about 80mA not exceed. But enough will usable small-sized circuit has comfortablely. Think I uses Zener Diode be formed help maintain one’s position volt be stable , and use Transistor help enlarge current tallly increasingly. Make this circuit is usable well , But friends as a result must use the carefulness specially , because apply to the level voltage tall directly yes.