This is a simple DC loop. Effort they can to 5 V and 12 V 12V zener diode 2N3055 transistor and the base of the segment. allows you 12V 15V up well enough to maintain a stable voltage. Change the integrated circuit LM309 for the acquisition of approximately 5 V is applied to the normal set of digital circuits. If you select the frequency 0.1μF, C3 disturb the good of all. For more details, friends and teachers ask to see the circle.
