Principle of sound-light control delay switch circuit board:
Acousto-optic control delay switch is mainly composed of sound control switch, light control switch and delay circuit. Voice control is to collect sound through the pole microphone, and generate pulse signal. The light-controlled circuit is controlled by photosensitive resistors. The resistance value of photosensitive resistors varies greatly in the condition of light and no light, which can produce high and low levels and control the circuit through logic devices. The delay circuit is composed of a resistor and capacitor charging and discharging circuit, through the capacitor charging and discharging to achieve. The most commonly used delay circuit is 555, relying on external capacitance and resistance to control the time, easy to calculate, the disadvantage is that the delay time can not be very accurate.

Acousto-optic control refers to the use of sound and light changes to control the circuit to achieve a specific function of an electronic control method. Acousto-optic control delay and power saving circuit includes sound control, light control sensor, amplifier and composed of 555 monostable delay circuit and buck rectifier circuit. It is an energy-saving electronic switch with no contact point inside, which can activate the pickup with sound effect to control the opening of electrical appliances under specific environmental light, and can automatically disconnect the power supply after delay. Widely used in corridors, building corridors, washrooms, toilets, factories, courtyards and other places, is a modern ideal novel green lighting switch, and extend the service life of the bulb.

Simple and practical sound-light control switch
This kind of sound and light control delay switch is not only applicable to the corridor of residential areas, but also applicable to the public places such as factories, office buildings, teaching buildings, etc. It has the advantages of small size, beautiful appearance, easy production, reliable work, etc. It is suitable for the majority of electronic lovers to make themselves.

First, the working principle of the circuit

The circuit schematic diagram of the sound-light control delay switch is shown in the figure. The main component of the circuit is the use of digital integrated circuit CD4011, its internal contains four independent and non gate D1~D4, the circuit structure is simple, high reliability.

As the name suggests, sound-light control delay switch is to use sound to control the switch “open”, a few minutes after the delay switch “automatically close”. Therefore, the function of the whole circuit is to turn the sound signal into an electronic switch after processing. After the signal flow direction of the circuit is defined, the circuit can be divided into several units according to the main components, from which the block diagram shown in Figure 2 can be drawn.

Analyze Figure 1 in conjunction with Figure 2. Sound signals (footsteps, clapping, etc.) are received by the electret microphone BM and converted into electrical signals, which are coupled to D3 by C1 for voltage amplification. At this time, the amplified signal is sent to one end of R3, which forms a voltage divider circuit and is connected to the foot of the control gate D4 as a sound control signal. When there is a sound signal, pin 10 is the high level “1”, then the intermediate partial voltage of R3 and R4 is the low level “0”, that is, the pin of control door D4 is the low level.

In order to make the sound-light switch switch off in the daytime, namely, the photosensitive resistor RG and other components form the photosensitive circuit, R6 and RG form the series voltage divider circuit. When there is no ambient light at night, the resistance value of the photosensitive resistor is large and the voltage at both ends is high, then the pin 1 of the NAND gate D1 is the high level “1”, and through the NAND gate D1 is the low level “0”. Then through the diode D1 input to the control door pin 13, also for the low level “0”. So that the sound-light control circuit work with the light control conditions. Strong daytime conditions make the resistance of RG very small. The voltage at both ends of RG is almost zero, which is the low level “0”. Then the pin 1 of the and and not gate is low level? 0 ‘, so that the sound-light control circuit does not have the condition of light control, and the electronic switch is in the disconnected state.

At night, when there is external sound signal, one end of the input end of the control gate (and non gate)D4 is at the low level “0” and the output is at the high level “1”. Make one-way thyristor conduction, electronic switch closed; To C3 charging at the same time, the C3 and R5 delay circuit, delay time, to change the value of C3 or R5, may change the delay time, meet different delay requirements, C3 to R5 only after electric discharge, when the discharge to a certain electricity at ordinary times, the input end of the nand gate D2 5, and 6 feet as low level, the output of high level, the nand gate 12 feet for high level “1”, at the same time there is no sound signal with gate 13 feet for high level “1”, the two input nand gate D4 for high level, then its output is low level? 0 ‘, so that the unidirectional SCR cutoff. The electronic switch is disconnected, completing a complete electronic switch from on to off process.

Diodes VD1~VD4 will AC bridge rectifier. It becomes a pulsating direct current, and after step-down, C4 filtering is the DC power supply of the circuit. Power supply for BM, IC, etc.

II. Selection of components

CMOS digital integrated circuit is selected. CD4011 has four independent AND gate circuits, internal functions are shown in Figure 3. VSS is the negative pole of power supply. The VDD is the positive terminal of the power supply. SCR T /4OOV imported one-way SCR 1006 type, such as large load current can be used to select 3A, 6A, 1OA and other specifications of one-way SCR, its measurement method is: file. The red pen is connected to the silicon controlled electrode, the black pen is connected to the positive pole, then the needle no reading, and then touch the control pole K with a black table, then the table has a reading, the black pen immediately left when the table is still reading (note that the touch control pole is always connected to the positive and negative table) that the silicon controlled is intact. The electret is a small microphone for general radio cassette recorders. Its measurement method is: the red pen with a file connected to the shell S, black pen D, then blow on the electret with the mouth, if the electret swing means that the electret is intact. The larger the swing, the higher the sensitivity; The photosensitive resistor is type 625A. When there is light, the resistance is below 20K, and when there is no light, the resistance value is greater than 1OOM0, indicating that the component is in good condition. The diode is a common rectifier diode ~1N4007. In short, the selection of components can be flexible, parameters can be selected in a certain range. Other components can be labeled as shown in Figure 1.

Three, installation and production

Check the list of components to buy electronic components, the first check the list of materials will be carefully counted again, and use a multimeter roughly (because the factory has measured the components. Know what you’re doing.

When welding, pay attention to welding non-polar resistance-capacitance elements first. The resistors are mounted horizontally and the capacitors are mounted vertically and are attached to the circuit board. Welding polar components such as electrolytic capacitors, microphones, rectifier diodes, audions, unidirectional thyristor and other components should not be installed in reverse, pay attention to the correct polarity, otherwise the circuit can not work properly or even burn components.

Four, debugging,

Before debugging. First, the welded circuit board is carefully checked against the circuit diagram, and there should be no wrong welding, leakage welding, short circuit and other phenomena. After energizing, the human body is not allowed to contact any part of the circuit board to prevent electric shock and pay attention to safety. If use multimeter to detect. Contact the two pens of the table with the corresponding circuit board.

When debugging this circuit, please block the light of the photosensitive resistor. Connect the AB to the switch position of the lamp and tap the electret with your hand. At this time the light should be on, if the light illuminates the photosensitive resistor, and then beat the electret with your hand, then the light is not on. It indicates that the photosensitive resistance is intact, and the production is successful. If not, please check carefully whether there are false missoldering and short circuit phenomenon of dragging tin