Sound-controlled light-controlled lamp production

Sound-controlled light-controlled lamp production

The sound-controlled or light-controlled energy-saving lamp made of NE555 integrated circuit or sound-controlled integrated circuit (such as BH-SK-Ⅰ, BH-SK-Ⅱ) or photoresistor is relatively common. It can not only extend the service life of the bulb, but also eliminate the "always on lamp" phenomenon. This article introduces a sound-controlled and light-controlled energy-saving lamp composed of common electronic components. It is very suitable for beginners of electronic technology to make small productions, so you may as well give it a try.

1. Working Principle
The figure below is the circuit diagram of the sound-controlled and light-controlled energy-saving lamp. The circuit consists of the main circuit, switch circuit, detection circuit and amplifier circuit.

The four diodes (VD1-VD4) that make up the bridge rectifier and a unidirectional thyristor (VS) form the main circuit (connected in series with the light bulb); the switching circuit is composed of the switching transistor VT1 and the charging circuit R2, C1; the amplification circuit is composed of VT2-VT5 and resistors R4-R7; the piezoelectric piece PE and the photoresistor RL constitute the detection circuit; the control power supply is composed of the voltage regulator tube VD5 and the resistor R3.

After the AC power is rectified by bridge and divided by resistor R1, it is connected to the control electrode of the thyristor VS, so that VS is turned on (VT1 is turned off at this time); because the light bulb, diode and VS form a path, the light is on. At the same time, the rectified power supply charges C1 through R2: if the gate voltage of VT1 is reached, VT1 is saturated and turned on, and the thyristor is turned off and the light goes out. In the absence of light and sound, an electrical signal is obtained on the piezoelectric chip, which is amplified to turn on VT2. C1 discharges through VT2 to turn off VTl, and the thyristor controls the extremely high potential to turn on VS and turn on the light. As R2 and C1 are charged, the light automatically goes out.

Adjusting R5 changes the size of negative feedback, so that the sensitivity of receiving sound signals can be changed, thereby adjusting the sensitivity of the lamp. The photoresistor and the piezoelectric chip are connected in parallel. When there is light, the resistance value becomes smaller, causing the electrical signal induced by the piezoelectric chip to lose too much and cannot be amplified. VT2 is turned on, so the lamp does not light up.

2. Component selection
VD1-VD4 can use 1N4004 (of course, rectifier bridge stacks such as BR108, RS307, etc. can also be used), VT1-VT5 can use 9011, VS can use 1~400V plastic tube (such as MCR100-16, MCR100-8), etc., R2 can use 0.5W carbon film resistor. R1-R6 can use 1/8W carbon film resistor, C1 can use 47μ/10V capacitor, C2 and C3 can use 10μ/10V capacitor, among which C1 has higher requirements. VD5 can use 2CW10 (stable voltage is 2-3.5V), piezoelectric sheet φ5-φ15, and the dark resistance of the photoresistor is required to be above 1 MΩ.

3. Installation and debugging
The actual size of the printed circuit board of the energy-saving lamp is 40mm × 30mm. When installing, you can install the main circuit first, and then you can experiment. If feasible, go a little further to install the detection circuit and the amplifier circuit, and finally install the photoresistor. The photoresistor can be selected from the MG45-32 or MG45-34 series non-sealed type; the piezoelectric piece can be selected from the φ27 piezoelectric ceramic piece, which requires high sensitivity. Do not use inferior products or mail-order amateur products, otherwise the sensitivity will be greatly reduced. The piezoelectric ceramic piece should be installed in a cavity dome with resonance performance. Since it only reacts to sudden sounds and is insensitive to continuous and slowly changing sounds, it has a strong anti-interference ability (if an electret microphone is used as a sound sensor. Although the sensitivity can be improved, the anti-interference ability will be reduced a lot). After assembly, it can be placed in a small box with a moderate volume (such as a pocket radio shell, etc.).

The function of this energy-saving lamp is: the lamp is off when there is light, and it will only light up when there is no light (at night) and there is sound. The lamp will automatically turn off after a period of time (about 2 minutes); the lamp will turn on again when there is sound again. This lamp is particularly suitable for use in public places, such as corridors on floors, doorways of dormitories, etc., so that it will automatically turn off at night without people turning off the lights, which saves electricity and prolongs the service life of the bulb. When it comes to 200V mains electricity, please pay attention to safety!