Advertising lantern production circuit design - signal processing electronic circuit diagram

　　Circuit principle: Each 8050 transistor can drive twelve to twenty-four light-emitting diodes. If Q1 and Q2 are changed to 9013, the number of driven LEDs will be halved. Only light-emitting diodes with the same luminous voltage (light-emitting voltages of different colors are generally different) can be used in parallel. The light-emitting diodes can be connected into the required pattern to express the designer's intention. The flashing period of the colored lights is: T=0.7&TImes;（R1+R3）&TImes;C2+0.7&TImes;（R2+R4）&TImes;C1 Select the parameters of R1, R2, R3, R4, C1, and C2 according to the flashing speed requirements. . Adjust the size of potentiometers R1 and R2 to change the flashing speed. Excessive voltage will burn out the light-emitting diodes. Increase the working voltage starting from 3v. When the power supply voltage is higher than 5v, a 2.2-27 ohm resistor should be connected in series as a current-limiting resistor to avoid burning out the light-emitting diode.

　　SCR is a new type of semiconductor device. It has the advantages of small size, light weight, high efficiency, long life, fast action and easy use. Currently, AC voltage regulators mostly use SCR voltage regulators. Here we introduce a thyristor AC voltage regulator with a simple circuit, easy installation and convenient control, which can be used as a voltage regulating device for household appliances for control. In the picture, RL is the load (lighting lamp, electric fan, electric iron, etc.). The output power of this voltage regulator reaches 100W, which can be used by general household appliances.

　　Circuit principle: The thyristor AC voltage regulator consists of two parts: a controllable rectifier circuit and a trigger circuit. The circuit principle diagram is shown in the figure below. It can be seen from the figure that the diodes D1-D4 form a bridge rectifier circuit, and the double-base diode T1 forms a relaxation oscillator as a synchronous trigger circuit for the silicon controlled thyristor. When the voltage regulator is connected to the mains, the 220V alternating current is rectified by the diodes D1-D4 through the load resistor RL, forming a pulsating DC voltage at the A and K ends of the thyristor SCR. This voltage is stepped down by the resistor R1 and serves as a trigger circuit. DC power supply. During the positive half cycle of the alternating current, the rectified voltage charges the capacitor C through R4 and W1. When the charging voltage Uc reaches the peak voltage Up of the single-junction transistor T1, the single-junction transistor T1 changes from off to on, so the capacitor C is rapidly discharged through the e, b1 junctions of the T1 tube and R2, resulting in a sharp point on R2. pulse. This pulse is sent to the control electrode of the thyristor SCR as a control signal to turn on the thyristor. The tube voltage drop after the thyristor is turned on is very low, generally less than 1V, so the relaxation oscillator stops working. When the alternating current passes through the zero point, the thyristor switches off automatically. When the alternating current is in the negative half cycle, the capacitor C is recharged, and again and again, the power on the load RL can be adjusted.

　　Component selection: The adjusting potentiometer of the voltage regulator uses a WH114-1 synthetic carbon film potentiometer with a resistance of 470KΩ. This potentiometer can be directly welded on the circuit board. The resistor except R1 must use a metal film with a power of 1W. Except for the resistors, the rest use carbon film resistors with a power of 1/8W. D1-D4 use silicon rectifier diodes with reverse breakdown voltage greater than 300V and maximum rectification current greater than 0.3A, such as 2CZ21B, 2CZ83E, 2DP3B, etc. SCR uses silicon controlled rectifier devices with forward and reverse voltages greater than 300V and rated average current greater than 1A, such as the domestic 3CT series.