Practical High Frequency Fluorescent Lamps: Traditional Chinese Circui

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High frequency fluorescent lampThe working frequency of fluorescent lamps sold in stores is 50Hz on the mains power supply. Its shortcomings are not only flickering, but also must be equipped with a ballast. At the same time, it is difficult to start when the mains power supply is lower than 190V.High-frequency fluorescent lamps work at a frequency of 50kHz. The fluorescent lamps not only have no flicker phenomenon, but also can eliminate the need for ballasts and starters. Under the same power consumption, the light is enhanced and the lighting is easy to start. It is also light-weight and energy-saving.1． How the circuit worksThe high-frequency fluorescent lamp circuit is shown in Figure 52-1. alt="52-1.jpg (20963 bytes)"> Figure 52-1After the power is turned on, the 220V AC power is stepped down by capacitor C1 and bridge rectified by D1~D2 to obtain DC voltage. This voltage is stabilized by capacitor C3 and voltage stabilizing tube DW to provide a stable DC working voltage to the time base integrated circuit IC, causing the IC circuit to oscillate. A square wave pulse is output at pin ③ of the IC and added to the gate G of the field effect transistor BG, and BG is turned on. The current after conduction is coupled to the coil L2 and capacitor C6 through the coil L1, which generates a higher induced electromotive force, causing the fluorescent lamp DL to ignite. When the induced electromotive force is too low to ignite the fluorescent lamp normally, push button switch K2 can be used. At the moment K2 is turned on, this electromotive force charges the capacitor C6, and its charging current is added to the ④ and ⑧ terminals of the IC through the diode D5, causing the voltage amplitude output by the IC pin ③ to increase. This voltage is added to the gate G of the BG, causing the impedance between the drain D and the source S of the BG to decrease. If the output current is larger, a higher induced electromotive force is generated, which is enough to ensure that the fluorescent lamp DL is ignited. After the fluorescent lamp is ignited, it replaces the closing function of K2 and continuously provides reliable operating voltage and current to the IC circuit, causing the IC circuit to oscillate. Pin ③ outputs a square wave voltage with a width of about 6μS, an amplitude of about 10V, and a frequency of 50kHz. This voltage is added to the grid G ​​of BG, causing the BG tube to turn on and off at a frequency of 50kHz, making the fluorescent lamp work in the frequency range of 50kHz, with a voltage peak of around 230V.The oscillation of the IC circuit is separately excited, and the resistor R2 and the capacitor C2 form a filter circuit.2. Component selection and debuggingThe IC is a time-based integrated circuit, and you can choose domestic 5G155, FX555, etc. or imported NE555.BG is a field effect tube, and imported 2SK320 can be used.DL is a fluorescent lamp with a power of 20~60W.L1 and L2 are inductor coils, which are composed of a single-strand plastic-coated wire wound side by side on the left and right 70 times on a ferrite core rod.D1~D6 are semiconductor diodes, choose 2CP type or 1N4002.DW is a voltage stabilizing diode, choose 2CW59 type or other types.R1 is 1MΩ and R2 is 100kΩC10.02μF withstand voltage 450VCC2100μF withstand voltage 160VC322μF withstand voltage 160VC4100μF withstand voltage 25VC70．1μF withstand voltage 15VC60.01μF withstand voltage 400VW is a 10kΩ potentiometerK1 is any type of toggle switchK2 is a reset button switchIn the absence of an oscilloscope, you can first place the potentiometer W in the middle position, then turn on the power supply K1, press the button switch K2 with your hand, and patiently turn the potentiometer W repeatedly to make the fluorescent lamp shine the brightest without redness or flickering at both ends.If you have an oscilloscope, use an oscilloscope to test the ③ pin of the time base integrated circuit 555 to output a square wave waveform and frequency, so that the square wave width is 6μS, the amplitude is 10V, and the frequency is 50kHz.The components of the high-frequency fluorescent lamp circuit are all installed on the same circuit board and installed in the box.The printed circuit of high frequency fluorescent lamp circuit is as shown in the figure52—2shown. …

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