Acousto-optic control delay switch is mainly composed of voice control switch, light control switch and delay circuit. Voice control is to collect sound through a cylindrical microphone and generate pulse signals. The light control circuit is controlled by the photoresistor, and the resistance of the photoresistor is very different when there is light and there is no light, which can generate high and low levels and control the circuit through logic devices. The delay circuit consists of a charge-discharge circuit composed of a resistor and a capacitor, which is realized by charging and discharging the capacitor. The most commonly used delay circuit is 555, which controls the time through external capacitors and resistors. The calculation is easy, but the disadvantage is that the delay time is not very accurate.

Acousto-optic control refers to an electronic control method that uses the change of sound and light to control the circuit to realize specific functions. Acousto-optic control time-delay power-saving circuit includes sound control, light control sensing elements, amplifier, monostable delay circuit and step-down rectifier circuit composed of 555.

It is an energy-saving electronic switch with no internal contact, which uses acoustic effect to excite the pickup to carry out acoustic-electrical conversion to control the electrical appliance to turn on, and can automatically disconnect the power supply after delay. Widely used in corridors, building corridors, bathrooms, toilets, factories, courtyards and other places, it is a modern ideal new green lighting switch, which prolongs the service life of light bulbs.

During the day or when the light is strong, the circuit is off and the light is off. When the light is dim or the night comes, the switch enters the preparatory working state. At this time, when there are sound sources such as footsteps, voices and applause. The switch is automatically turned on, the light is turned on, the automatic delay circuit is triggered, and it is automatically turned off after a period of delay, thus realizing "the light is turned on when people come and turned off when people leave", saving the ever-burning lamp and avoiding the need to turn off the light in the dark.