A simple automatic switch that can be activated and deactivated by sound. It is suitable for alarm systems and can be set to respond to voices, clapping, or other noises. It is so easy that even children can turn on the lights in a "magical way." Delivered with a relay and optical indication via LED. Simple construction with only five transistors. High sensitivity when using a condenser microphone. Operating voltage 9-12 VDC, maximum current consumption 125 mA, relay 250V-2A, board size 60x63 mm.