Single Rail Op Amp Power Supply

This stereo headphone amplifier uses a single rail power supply to operate from a single PP3 9 V battery. This means that the op-amp IC receives +9 V to the +Vcc pin, and 0 V to the –Vcc pin. Hence, the output signal can only swing between +9 V and 0 V, providing we offset the input signal to ½ Vcc. To produce this offset voltage, we use a pair of resistors in a potential divider configuration between the voltage rails. The centre of these two resistors is ½ Vcc, which connects to the non-inverting input to produce the offset.

LED Series Resistance

If you want to have an LED indicator for your amplifier then here is a simple circuit for that. The LED connects between Vcc and Ground. Please refer to the Series Resistance Calculator for LEDs article for more information.

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