Essential Dual Power Supply

The circuit, fed by a transformer with a single secondary winding, uses a half-wave rectifier on each rail, with BDX53 and BDX54 Darlington transistors and Zener diodes for voltage regulation. The output can deliver up to about 900 mA per rail, with a residual ripple of about 80 mV at full load, ensuring stable and reliable operation.

• Fed by a transformer with a single secondary winding
• Dual output voltage
• Half-wave rectifier on each rail
• Output voltage set by a Zener diode, according to the formula Vout = Vzener – 0.8V approx.
• Maximum current about 900 mA per rail
• Residual output ripple about 80 mV at 900 mA
• Recommended secondary voltage: Vzener + 4V approx. (for example about 15Vac for a 12V Zener)
• No current limiting.