This is a very sensitive sound switch circuit. In a previous topic we have shown a clap switch circuit that can activate a relay on any loud sound produced near microphone like whistle or clap etc. The circuit shown here is quite sensitive and it can hear sounds from many meters away and activate the relay
switch. The circuit can be used for numerous purposes where sound activation of any AC or DC device from distance is required.
The sound detection, amplification and control circuit is built around the transistor Q1, Q2 and Q3. The electret microphone detects the sound waves and converts them in to electrical audio signal these audio signals are amplified by Q1 and Q2. The transistor Q3 amplifies the rectified signal and sends it on the trigger pin 2 of 555 timer IC making it triggered and activates the LED and relay connected at the output pin 3 for a set time period. After the set time period is over the output of the IC at pin 3 goes low and the LED and relay will become deactivated. The activation time period of the LED and relay can be increase or decrease by increasing or decreasing the value of the capacitor Cx. The sensitivity of the circuit can be controlled by adjusting the 100K variable resistor.
Copyright 2013 © CircuitDiagram.Org. All rights reserved.
Sponsored Links
