At present, the application of white LED in the field of lighting is more and more extensive. I also have an interest in exploring it. So I bought some disassembled white LEDs according to your advertisement (LED (Light-Emitting-Diode) means LED It is a semiconductor capable of converting electrical energy into visible light. It changes the principle of incandescent tungsten light emission and energy-saving lamp three-base toner illumination, and uses electric field illumination. According to analysis, the characteristics of LED are very obvious, long life and light effect. High, no radiation and low power consumption. The spectrum of LEDs is almost entirely concentrated in the visible light range, and its luminous efficiency can exceed 150lm/W (2010).), prepare a LED table lamp.
First find an abandoned fluorescent tube table lamp, remove the circuit board in the lamp tube and the lamp holder; prepare two copper-clad plates, one piece of 88 light-emitting tubes connected in series, one with rectifying and filtering circuit components, the size is determined according to the actual situation. Full-wave voltage doubler rectifier circuit (the function of the rectifier circuit is to convert the AC voltage output from the AC step-down circuit to a unidirectional pulsating DC power. This is the rectification process of the AC power. The rectifier circuit is mainly composed of a rectifier diode. The voltage after the rectifier circuit is no longer an AC voltage, but a mixed voltage containing a DC voltage and an AC voltage, which is conventionally called a one-way pulsating DC voltage.) Powering the LED (as shown in the drawing). Two 0.68uF capacitors are both full-wave double-voltage rectifier circuit components and limited current. The capacitor is selected to withstand voltages above 400V, and the resistor is used at 0.25W. Because the circuit is simple, the circuit board is cut with a knife and the Φlmm welding hole is drilled at the pin position.
After the components are soldered, the 15kΩ/5W resistor is used as a dummy load to test the rectifier circuit. The resistor should have a DC voltage of about 280V. At this time, other components should not generate heat except the resistor. After all the normal, the lamp board is connected. After power-on, 88 LED tubes should be illuminated normally. Finally, the power board and the light board are respectively fixed on the base and the lamp cover. The brightness of the lamp is not as good as that of the original lamp, and the illumination area is small, but the reading and writing is still acceptable. After the lighting for a period of time, the temperature of the lamp plate rises, but the temperature is much lower than that of the fluorescent tube. The load loop current is measured to be about 18 mA, and the voltage across the lamp board is about 280 V, and the power consumption is about 5 W.
Pay attention to the production, welding must not have virtual welding, LED should be tested one by one and the polarity should not be soldered incorrectly; the power supply line should be installed with a fuse with a current less than 200mA; after the power is off, the capacitor has high voltage to pay attention to safety; the circuit can not be broken Open the load, otherwise the voltage of about 600V may damage the component.
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