Power Supply
The Power Supply Stage provides energy and bias voltage to all the circuitry, the whole power consumption is estimated in 40W:
The schematic is based in a 220VAC to ±12.6VAC center tapped transformer with a full wave rectifier followed by a shunt regulator.
Supply Regulation:
A Shunt Regulator is used to stabilize the supply at 15V. It is simple circuit based on a single Zener diode (two diodes ZD1 and ZD2 for dual supply ±15).
The output voltage of the regulator can never be higher than the Zener voltage (15V). The resistors R35 and R36 separate the regulator’s input and output voltage (including ripple) from each other and prevents the Zener from directly loading and shunting the supply. Shunt regulator is always quite inefficient due to the constant power loss over the series resistors.
The Power Supply Stage provides energy and bias voltage to all the circuitry, the whole power consumption is estimated in 40W:
The schematic is based in a 220VAC to ±12.6VAC center tapped transformer with a full wave rectifier followed by a shunt regulator.
- The capacitors CX1 and CX2 are surge suppressor filters that attenuate mains and switching transients.
- The Fuse protects the device from dangerous inrush currents shutting down everything in case of failure.
- The power-on LED3 diode attached to +15V indicates the correct power supply state.
Supply Regulation:
A Shunt Regulator is used to stabilize the supply at 15V. It is simple circuit based on a single Zener diode (two diodes ZD1 and ZD2 for dual supply ±15).
The output voltage of the regulator can never be higher than the Zener voltage (15V). The resistors R35 and R36 separate the regulator’s input and output voltage (including ripple) from each other and prevents the Zener from directly loading and shunting the supply. Shunt regulator is always quite inefficient due to the constant power loss over the series resistors.