Beautiful and practical intelligent sound and light control corridor lights

Every time I go home and walk up the stairs, I am always scared. The corridor lights are often broken, and no one changes the bulbs, or they are not smart enough and need to be operated manually. Especially when I get to the door to get the key, the corridor lights are off and need to be re-lit. So I imagined that if I could make a sound and light controlled corridor light by myself, and fix it on the door with mosquito nails: when someone walks through the staircase at night, when there are footsteps or other sounds, the corridor lights will automatically light up and provide lighting; when people enter the house or walk out of the apartment, the corridor lights will automatically go out after a delay of a few minutes. In the daytime, even if there is sound, the corridor lights will not light up, which can achieve the purpose of energy saving.

This sound and light controlled delay switch is not only suitable for the corridors of residential areas, but also for public places such as factories, office buildings, and teaching buildings. It has the advantages of small size, beautiful appearance, easy production, and reliable operation, and is suitable for self-made by the majority of electronics enthusiasts.

1. Working principle of the circuit

The circuit schematic diagram of the sound and light controlled delay switch is shown in the figure. The main components in the circuit are the digital integrated circuit CD4011, which contains 4 independent NAND gates D1~D4, with a simple circuit structure and high reliability.

As the name implies, the sound and light controlled delay switch uses sound to control the "opening" of the switch, and the delay switch "automatically closes" after a few minutes. Therefore, the function of the entire circuit is to process the sound signal and convert it into the switching action of the electronic switch. After clarifying the signal flow of the circuit, the circuit can be divided into several units according to the main components, and the block diagram shown in Figure 2 can be drawn.

Analyze Figure 1 in conjunction with Figure 2. The sound signal (footsteps, applause, etc.) is received by the electret microphone BM and converted into an electrical signal, which is coupled to D3 through C1 for voltage amplification. The NAND gate D3 is an amplifier circuit at this time, and the amplified signal is sent to one end of R3. R3 and R4 form a voltage divider circuit and are connected to the pin of the control gate D4 as a voice control signal. When there is a sound signal, the 10th pin of is a high level "1", and the intermediate voltage of R3 and R4 is a low level "0", that is, the pin of the control gate D4 is a low level.

In order to make the sound and light control switch disconnect during the day, a light control circuit is formed by components such as photoresistor RG, and R6 and RG form a series voltage divider circuit. When there is no ambient light at night, the resistance of the photoresistor is very large, and the voltage at both ends is high. Then the 1st foot of the NAND gate D1 is a high level "1", and it is a low level "0" through the NAND gate D1. Then it is input to the 13th foot of the control gate through the diode D1, which is also a low level "0". The sound and light control circuit has the conditions for light control. The strong environment during the day makes the resistance of RG very small. The voltage at both ends of RG is almost 0, that is, a low level "0". Then the 1st foot of the NAND gate is a low level? 0', so that the sound and light control circuit does not have the conditions for light control, and the electronic switch is in the disconnected state.

At night, when there is an external sound signal, one end of the input end of the control gate (NAND gate) D4 is low level "0", and the output is high level "1". The unidirectional thyristor is turned on and the electronic switch is closed; at the same time, C3 is charged, and C3 and R5 form a delay circuit. The delay time can be changed by changing the value of R5 or C3 to meet different delay requirements. After C3 is fully charged, it only discharges to R5. When it is discharged to a certain level, the input ends 5 and 6 of the NAND gate D2 are low level, the output is high level, and the 12th foot of the NAND gate is high level "1". At the same time, when there is no sound signal, the 13th foot of the NAND gate is also high level "1". The two input ends of the NAND gate D4 are high level, and its output is low level? 0', which turns off the unidirectional thyristor. The electronic switch is disconnected, completing a complete process from opening to closing of the electronic switch.

Diodes VD1~VD4 perform bridge rectification on the AC, turning it into pulsating DC, which is then stepped down and filtered by C4 to become the DC power supply of the circuit, supplying power to BM, IC, etc.

2. Selection of components

The CMOS digital integrated circuit is selected. CD401 1 has four independent NAND gate circuits. The internal function is shown in Figure 3. Vss is the negative pole of the power supply. VDD is the positive pole of the power supply. The thyristor T uses the imported unidirectional thyristor 1006 type of /4OOV. If the load current is large, unidirectional thyristors of specifications such as 3A, 6A, and 1OA can be selected. Its measurement method is: use the gear. Connect the red test pen to the negative pole of the thyristor and the black test pen to the positive pole. At this time, the needle has no reading, and then touch the control pole K with the black test pen. At this time, the meter has a reading. The black test pen is immediately removed. At this time, the meter still has a reading (note that the positive and negative test pens are always connected when touching the control pole), indicating that the thyristor is intact. The electret uses a small microphone used in general recorders. Its measurement method is: use the gear to connect the red test pen to the S of the shell and the black test pen to D. At this time, blow air to the electret with your mouth. If the needle swings, it means that the electret is intact. The larger the swing, the higher the sensitivity; the photoresistor is 625A type, the resistance is below 20K when there is light, and the resistance value is greater than 1OOM0 when there is no light, indicating that the component is intact. The diode uses an ordinary rectifier diode ~ 1N4007. In short, the selection of components can be flexibly mastered, and the parameters can be selected within a certain range. Other components can be marked as shown in Figure 1.

3. Installation and production

After buying electronic components, first check the materials list carefully and use a multimeter to roughly measure each component (because they have been measured before leaving the factory).

When welding, be sure to weld non-polarized resistors and capacitors first. Resistors should be installed horizontally and capacitors should be installed vertically, close to the circuit board. When welding polarized components such as electrolytic capacitors, microphones, rectifier diodes, transistors, thyristors, etc., do not install them in reverse. Pay attention to the correct polarity, otherwise the circuit will not work properly or even burn out the components.

4. Debugging

Before debugging, carefully check the soldered circuit board against the circuit diagram to avoid wrong soldering, missing soldering, short circuit, etc. After power is turned on, the human body is not allowed to touch any part of the circuit board to prevent electric shock and pay attention to safety. When using a multimeter for testing, just touch the two probes of the multimeter to the corresponding parts of the circuit board.

When debugging this circuit, please block the light of the photoresistor. Connect AB to the switch of the light, and tap the electret with your hand. The light should be on at this time. If you shine light on the photoresistor and tap the electret again, the light will not be on. This means that the photoresistor is intact, and the production is successful. If it is unsuccessful, please carefully check whether there is false wrong soldering and tin drag short circuit phenomenon.