Traditional Chinese Billboards that can change three screens (Workshop Practice) — Circuit, Wiring & Debug Guide

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A billboard that can change between three imagesOur country's advertising industry has become increasingly prosperous with the development of economic reform. In today's fierce product competition, advertising is imperative.At present, there are a dazzling array of product advertisements on the streets, but the common disadvantage is that the advertising images are fixed and devoid of freshness. When night falls, these advertisements lose their advertising effect due to the lack of lights. A better advertisement is equipped with color-changing fluorescent lights to add a bit of character to the advertisement. computer program controlAlthough advertising boards are advanced, they are expensive and ordinary units do not have the economic power to install and use them. Therefore, it is necessary to find a novel and practical advertising device to make it truly effective in advertising.The billboard that can change three kinds of images is designed for this purpose. It can periodically change the advertising cycle of three different products. It not only accommodates a lot of content, but also is fresh and eye-catching. Not only does it have an advertising role during the day, it also shines brightly at night, adding a dazzling three-dimensional image to the city. It is not only suitable for product manufacturers to assemble themselves, but also suitable for mass production by advertising manufacturers. The structure and installation methods of billboards that can change three kinds of images are now introduced as follows for the reference of interested manufacturers.1． How the circuit worksThe picture of this billboard is automatically timed and cycled, and the lights in the billboard are automatically lit when night falls. Its circuit control is shown in Figure 36-1.Figure 36-1In the figure, transistors BG1, BG2, relay J and other components form a billboard automatic timing conversion circuit, which is a self-excited multivibrator. When the BG2 tube is turned on, the relay J operates, the normally open contact J1 is closed, the power of the motor M is turned on, the motor rotates, and drives the billboard to change one screen. Then the BG1 tube is turned on, BG2 is turned off, the relay J is released, and the motor stops rotating. The time when BG2 is turned on is exactly the time it takes to convert a picture, and the time when BG1 is turned on is the time the picture needs to stay. By adjusting the resistance values of resistors R1 and R2 or changing the capacities of capacitors C2 and C3, the required dwell time and screen switching time can be achieved.Phototransistor BG3, time base integrated circuits IC1, IC2 and triac SCR, etc., form a light-controlled timing switch circuit. When entering the evening, the circuit automatically turns on and the lights in the billboard light up. After working for a few hours, the lights in the billboard automatically turn off.Its working principle is: when daytime light shines on the phototransistor BG3, due to the reduction in light resistance, the BG4 tube is cut off, the BG5 tube is turned on, and the BG6 tube is cut off. The rear circuit cannot work without power supply voltage, and the triac SCR cannot be turned on because there is no trigger voltage, so the lighting lamp ZD installed in the billboard does not light up.After dark, due to the increase in the dark resistance of the phototransistor BG3, the BG6 tube is turned on, turning on the power supply of the rear circuit, causing the oscillation circuit composed of IC1 and others to start oscillating, and the ③ pin of IC1 will continuously output pulse voltage. Since the charging time constant of capacitor C6 is large, and the oscillation period of the oscillator circuit T < W2C6, the voltage on capacitor C6 is lower than 1/3 of the power supply voltage when starting to work, causing the output of pin 3 of IC2 to be high level, triggering the triac SCR to turn on, and lighting lamp ZD to light up. Thereafter, under the action of the charging pulse, as long as the oscillation circuit satisfies the charging time T1 to be greater than the discharging time T2, and T1 + T2 < W2C6, the voltage on the capacitor C6 can gradually rise in the process of charging and discharging. The rising speed is achieved by adjusting the time constants T1 and T2 and changing the values of W2 and C6. When the charging voltage on capacitor C6 rises to greater than 2/3 of the power supply voltage, the trigger circuit composed of IC2 and others immediately flips over, and the ③ pin of IC2 changes from high level to low level. The control electrode of the triac SCR is turned off due to the loss of trigger voltage, and the lighting lamp ZD goes out. In this way, the lighting in the billboard will not light up during the day; it will automatically light up when it gets dark, and will automatically turn off when it lights up for a specified time, avoiding the need to keep the lights on at night and saving electricity.2. Component selectionB is the power transformer, which can be modified with the 36V power transformer on the lathe. The original winding remains unchanged. When removing the secondary winding, find out the number of turns per volt, and rewind the secondary winding according to L2 as 9V and L3 as 24V. If the motor uses a low-power AC motor with a reducer (such as a control motor in an electric fan), the secondary winding L3 is not required, as long as a finished power transformer with an output voltage of 9V is used.IC1 and IC2 are time base integrated circuits, and μA555, LM555 or other types of time base circuits can be selected.Capacitors C5 and C6 should be tantalum electrolytic capacitors with small leakage current, high precision, and less affected by ambient temperature; resistors should be metal film resistors with high precision and small errors.J is a 9V DC relay, you can choose JRX or JRC type.SCR is a bidirectional thyristor with a withstand voltage of 450V. The operating current depends on the power of the bulb used. Generally, 3A can meet the requirements.D1~D5 are diodes, optional 2CP16 or 1N4004.BG3 is a phototransistor, using 3DU5 or photoresistor.BG1, BG2, BG6, choose 3DG6 or 9014.Choose 3DK2 or 3DK4 for BG4; 3DG12 for BG5.R15.6kΩR2, R3120kΩR56kΩR52．4kΩR6750ΩR7200ΩR8, R9100kΩW1220kΩ trimming resistorW21MΩ trimmer resistorC1100μF／16VC247μF／16VC3200μF／16VC4220μF／16VC5, C64.7μF/16 …

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