This simple Sound-Activated Lamp circuit shown int the schematic diagram actives the switch
using sound. We can use this circuit for various applications, such as
automatic (sound-controlled) disco light or car’s LED light show. The
Q1 amplify the audio from mic. The R1 is used to adjust the peak of
signal to greater than about 0.7 volts, act as sensitivity adjuster. A
certain level, the signal coming from microphone, after amplification by
Q1, will trigger the SCR and light lamp I1. If we change the lamp with a
relay, then we can get a sound-activated relay/switch, which can be
used to control more powerful / high wattage high voltage lamps. If we
use a relay, place a 1N4007 diode in parallel with the relay coil to
prevent the back-emf from relay coil destroying the SCR.
Sound-Activated Lamp Circuit Diagram
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