What is the basic principle of the sound and light control electronic switch circuit?

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/ 2019-07-22 / News

Sound and light control electronic switchcircuit is mainly composed of voice control circuit. Light control circuit. Trigger and delay circuit. Control circuit power supply circuit. Controlled circuit and other components, in fact, this circuit is mainly used for night or light dim time, can play the role of automatic control, when there is sound in the external environment, the switch will be activated, the bulb will automatically light up, one minute It will automatically go out afterwards. In the daytime, when the light is strong, no matter whether there is sound in the environment, the switch will not be activated, and the light bulb will naturally not light up, achieving the purpose of energy saving.

How it works:

What is the basic principle of the sound and light control electronic switch circuit

1, daytime

when daylight is strong The photosensitive transistor is turned on, the resistance is small, and the potential of the opposite end (9-pin) of the comparator A3 rises above 5V, and the comparator output is low. Level, diode VD1 is turned on, VD2 is turned off, the signal output from the voice control circuit is sealed, and the thyristor is present regardless of the presence or absence of a sound signal. It won't turn on and the lights won't light up.

2, night

When the night When the light is very dark or late, the photosensitive transistor is cut off, the resistance is large, and the potential of the opposite end (9-pin) of the comparator A3 is lowered, below 5V, and the comparator output is high. , diode VD1 is cut off,At this time, the signal of the non-inverting terminal of the voltage comparator A4 is completely dependent on the output state of the operational amplifier A2, that is, determined by the voice control circuit.

(1) When there is no sound input, MIC has no output signal, diode VD2 is turned off, and the non-inverting terminal of comparator A4 ( 12 feet) The potential is less than the potential of the inverting terminal, the comparator A4 outputs a low level, the control electrode of the thyristor has no trigger signal, the thyristor VT is not conducting, and the lamp is not lit.

(2) When there is sound input, the MIC outputs a smaller audio signal, which is input through the input The coupling is sent to the operational amplifier A1 for the first amplification, and then the second amplification is performed by the A2. The amplified audio signal is sent to the non-inverting terminal (12-pin) of the comparator A4 through the diode VD2, and the comparator A4 outputs a high level, and the thyristor has a trigger signal to turn on the thyristor VD, and the light is on.

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