This circuit presents a very simple and useful stereo balance indicator circuit that is based on few common external components. This schematic circuit is very simple to build. An visual indication with LEDs for left , right and center balance is provided by this circuit.
Outputs from each channel are fed to the two inputs of IC1 connected as a differential amplifier. Output of the IC1 is connected to the noninverting inputs of the IC2 and IC3. The outputs of the IC2 and IC3 will go high illuminating the LED 3 , this will show that the right channel is dominating if he outputs of the IC1 approaches the supply rail. The IC2 and IC3 will go low and the LED1 will light if the sound is balanced to the left channel. The outputs of the IC2 and IC3 would be low and high respectively , lighting up LED2 if both channels are equal in amplitude. This sound balance audio circuit diagram need to be powered by a 15 volts power supply. The operational amplifier circuit diagram it is a TL084 operational amplifier.