Use CD4011 to make a sound and light dual control delay lamp (2)

This circuit mainly uses a 2-input four -NAND gate digital integrated circuit, in which NAND gate III forms the microphone amplifier
circuit; NAND gate IV forms the "AND gate" for light control and signal amplification to control i, NAND gate I and NAND Gate II forms a monostable delay
control circuit. The power supply used in the entire circuit is supplied by resistor R8 for voltage reduction, VD2 for half-wave rectification, and capacitor C4 for filtering.
    In the static state, the input terminal of NAND gate III is connected to the positive power supply because R2 is connected to the positive power supply, so the output terminal lo pin is low level. The logic "O" of NAND gate IV pin 12
makes the logic "O" of l3 pin no matter whether it is day or night. Logic "1", its output pin 11 always outputs
logic "1". The logic "0" at the input terminals 5 and 6 of NAND gate II causes the output terminal 4 to output logic "1", so at this time,
the two input terminals 1 and 2 of NAND gate I are both logic "1", Output 3 is logic "O". When the alternating current is a positive half cycle (ie,
upper positive and lower negative), the thyristor vs is cut off without conduction conditions. At this time, the alternating current is rectified by VD2 half-wave to provide power for the circuit
. When the alternating current is a negative half cycle (i.e., upper negative and lower positive), resistors R8 and R7 are connected in series to provide trigger current for vs. Since pin 3 outputs logic "O" in
the static state , the forward current passes through R7, R6, VD1 and the NAND gate. Pin 3 of I is connected to the ground, the gate of vs is at
low level, and vs is turned off, so the light H does not light up.
    When microphone B receives the environmental sound wave signal, it outputs a corresponding electrical signal. This signal is coupled through cl and sent to
the input terminals 8 and 9 of NAND gate III. The amplified signal is output by the IO pin. When the positive half-cycle bee value of the audio signal exceeds the threshold
level of NAND gate IV, NAND gate IV flips. Pin II outputs logic "0" (assuming the environment is dark at this time and pin 13 is logic level "1"),
so pin 3 of NAND gate I outputs logic "l", the diode VDI is cut off, and vs is triggered by R7 When the current is turned on,
the lamp H lights up and emits light. At the same time, the high level of pin 3 causes the input
pins , so the output pin 4 outputs logic "O" and is directly added to the AND Pin 2 of NOT gate I. At this time, even if
the level of pin 10 changes with the audio frequency, pin 1 of NAND gate I is logic "l", but because pin 2 is logic "O", pin 3 is
guaranteed to output logic "l". Therefore, lamp H can still remain lit. When the light is on, the high level of pin 3
charges capacitor C3 through R5, causing the voltage across the capacitor to continue to increase. Therefore, the level of input terminals 5 and 6 of NAND gate I1 continues
to decrease. When the level is lower than the NAND gate input threshold, pin 4 will output logic "l". If there is no sound in the environment at this time, If pin 1
is also logic "l", then pin 3 outputs logic "O", the thyristor VS is turned off, and the light H goes out. If there is sound in the environment again,
the light can be lit again. The duration of the lamp lighting is mainly determined by the charging time constant of R5 and C3.
    R4 and photodiode VD3 form a light control circuit. VD3 has a high resistance at night, making pin 13 a high level "l".
At this time the level of pin II at the output terminal of NAND gate IV only depends on the level change of pin 12. , that is to say, it only depends on whether there is sound in the surrounding environment
. During the day, VD3 has low resistance, making pin 13 at logic "0", thereby blocking the NAND gate IV, making
the thyristor Vs not controlled by ambient sounds, and the lamp H will never light up.