The IC1 opam functions as a stable power multivibrator. Its oscillation frequency is determined by C3. Its oscillates at around 4kHz at standby and increases in a loaded condition up to around 7kHz. The output of the IC2 opamp is identical to the IC1 oscillator signal but in the opposite phase.

When the output of IC1 is at zero, the C4 charges via the diode D1 up to the power supply level minus the voltage drop at D1. When the IC1 swings to the opposite direction, its output become positive. The output voltage from IC1 adds up to the voltage stored at C4 forcing the diode D1 to stop conducting. C5 then charges via the diode D2 to a voltage that is double than the power supply level.

The theoritical output could reach the triple of the supply voltage. TO guard against unnecessary voltage increases at low current consumptions, a limiter stage was added to the circuit composed of a 15 volt zener diode and a darlington transistor T1/T2. This stage caps the output voltage to about 14.2 volts. To fiter out ripple from the output, C8 was also added. This helps prevent the hum signal from being noticed on radio or audio devices.

In constructing the 6 to 12 volts converter, attach the ICs to a common heatsink close to the pcb. THe transistor must be attached to a separate heatsink. To get a much higher current output from the converter, C4, C5 and C6 must be increased to 2200uF.

6 to 12 volts converter schematic

6v to 12v converter pcb layout

12V dc power supply schematics

12V BD139 power supply circuit

LM7812 power supply schematic
A very simple PS circuit with the basic 3 Amper version of LM7812 IC.

LM317 variable power supply circuit

2N3055 adjustable power supply schematic
This PS circuit has a over-current protection and a good stabilized voltage. It can deliver up to 1.6 A.