How to assemble a super simple Stereo Balance Indicator

Introduction

Nowadays stereo audio amplifiers are in use aplenty among all walks of people. They may be music lovers, professionals, learners, students and even trainees in any walk of life. Normally stereo audio amplifiers come fitted with multifunctional controls. among them, volume, tone  and balance controls are common utility facilities. Stereo amplifiers should deliver equal sound output from each channel speaker namely Left, Right. Left channel and right channel audio outputs are delivered to the human ears through the two speakers connected to each channel output. 

It is normally expected to deliver equal volume/sound from the speakers. Inexpensive models you may find one additional control called' Balance'. it is to be adjusted and set to give an equal volume of sound from both the speakers. But when you set the balance control truly to the balanced position it may not give exact balanced output. further human ears find it very difficult to set the volume exactly equal. human ears may not be so sensitive to accurately place the balance control to the exact balance position. At that time a visual indication of correct settings of the balance control is a welcome utility add-on unit to stereo amplifiers. 

Balance Indicator

This add-on stereo balance indicator design is very simple and easy to assemble and fit into any stereo audio amplifier unit easily. It is very compact and economical to build. Can be set to exact accurate balance of both sound outputs namely left and right channel for the perfect stereo sound effects to enjoy. For accurate setting visual indication is used here. Two LEDs do this function to tell us whether the balance is real and accurate. The null effect of the balanced volume of sound makes the LEDs shut the glow and thus it is set to accurate and true effect. The circuit requires a 12V DC power supply for its operation and the same can be tapped from the main source power supply meant for the audio amplifier. 

The circuit schematic

The simple circuit schematic is given here. The circuit is straightforward and can be easily understood. 

Parts list 

Brief working of the circuit

To sum up

Very popular circuit for easy assembling even by a novice and can be assembled on any general-purpose PCB. Please provide your comments.