Public Address (PA) Circuits

Circuit Schematic Voice Operated Switch (VOX) using LM346 for Public Address Amplifier System - In public address amplifier, feedback is something that have to be avoided. The ideal solution of this is to adjust the speaker position and the microphone. However, many times is not possible doing so. Another solution is to using frequency shifter in order to change the output frequency 10Hz lower than the input frequency. However, for a low cost public address system, this solution is too costly. That why we need Voice operated switch.