The post details a simple sound activated relay switch circuit which can used as a module for any system that might be assigned to trigger by detecting some kind of sound pressure level.Or simply applications such as a sound activated alarm security circuit.
By: Arti singh gupta
Utilizing this sound activated switch, toggling a system by sound pulse could be very effective, not simply on a robot but as well as for some kind of home automation, as an illustration a sound-activated light bulb answering to a topple on the front door or a a hand clapping action.
The lighting is going to be promptly switched off after several seconds. An optional implementation is security protection system when someone aspires to break open the front door or ruin a thing, the light bulb may be expected to come ON on, indicating that someone uninvited is at your home.
The circuit could work from any 5-12 VDC controlled power source as long as a relay with the appropriate coil voltage is employed.
How the Circuit Works
As soon as you first associate the source voltage to the sound activated switch circuit, the relay will likely be energized on account of the impact of capacitor C2.
You must permit a couple of seconds for the relay to be flipped off. It is possible to maximize or minimize the ‘on’ time frame by modifying the uF C2.
A larger uF contributes to an extended ‘on’ span, and the opposite way round. However, you should not employ a value exceeding beyond 47μF.
Biasing resistor R1 establishes to a significant degree the microphone level of responsiveness. An electret microphone commonly possesses just one central FET inside which demands a bias voltage to run. The best possible bias degree for response to audio or noise level must have to be discovered by experimentation.
All of the related and useful electronic protection precautionary measures is required to be recognized each time while connecting mains powered loads to the relay contacts.
Parts List for the proposed sound activated relay switch circuit
R1 = 5k6
R2 = 47k
R3 = 3M3
R4 = 33K
R5 = 330 OHMS
R6 = 2K2
C1 = 0.1uF
C2 = 4.7uF/25V
T1, T2 = BC547
T3 = 2N2907
D1 = 1N4007
Relay = coil voltage as per the supply voltage, and contact rating as per the load specs
Mic = electret condenser MIC