As a technician and hobbyists, we are often faced with the problem of for the need the type of a voltage, where we had just the kind of asymmetric (+ and 0 V) while needs symmetrical (+, - and 0 V).
From the many circuits that I know, usually electronics friends make the power supply circuit from AC voltage asymmetric (NonCT) become a symmetrical voltage (+, 0, -) use IC L165 as the primary phase voltage convert so that it can be processed / in a split to 3 output voltages. But working the IC was very hard to need a large heatsink. However, on this occasion, I will share changer circuit a voltage to be symmetrical with utilizing asymmetric Capacitors, Diodes, Zener Diodes, and Transistors. For a circuit schematic can be seen below,
Circuit and PCB Design
Working Circuit:In the circuit scheme above, the AC voltage input from 220V AC output step-down transformer, where the output voltage of the transformer of 14.8V AC.
0V AC voltage direct entry into the diode and 14.8V AC enter directly to between series capacitors 1000uF/35V. AC voltage is processed by both of these components, so as to produce a DC voltage symmetrical (+,0,-) then filtered by two capacitors 1000uF/35V and 220uF/35V. At this point, I check the voltage around 76.6VDC +V and -V DC
The Voltage (+) and (-) 76.6VDC, for it symmetrical (+),(0V),(-) 33.3VDC. Then the voltage is lowered and regulated by using series transistor TIP31, TIP32, Zener12V, Rectifier Diode.
I'm using Zener Diode 12V then the output becomes +12V 0 -12V DC. If you want the output voltage +15V 0 -15V, use Zener Diode 15V.