With the development of electronic technology, the efficient energy-saving lamp with electronic ballast and daylight lamp tube is quietly entering thousands of households. It is found that electronic ballasts have two major disadvantages :(1) triode (such as C2482, etc.) is easy to damage, so that the life of energy-saving lamps is very short; (2) Low power factor, energy saving effect is not ideal.
The existing electronic ballast circuit is shown in the attached drawing. After rectification and filtering, the mains supply to the inverter circuit to make the inverter circuit work and light up the daylight lamp tube. The energy-saving lamp of this circuit is capacitive to the grid with a power factor of about 0.7. As a result of capacitor filtering, the dc voltage input inverter circuit, ripple coefficient is higher, but also cause pollution to the power grid, the greater interference to home appliances. The above problems can be effectively solved by making the following improvements to the circuit.
1. Reduce the filter capacitor capacity, the power factor can be increased to more than 0.85. The ripple coefficient can be reduced effectively by changing capacitor filter to passive filter. To do this, remove C1 from the attached drawing and replace it with the part shown by the dotted line. The capacity of C '1 and C' 2 varies with the wattage of the lamp: 4.7μF/250V for the use of the lamp tube below 15W; 10μF/250V when using 15-30W lamp, 22μF/250V when using 30W lamp. D '1 n4007.
2. The inductance coil L0 is connected in series at the input end of AC 220V, and the capacitor C0 is integrated, which can effectively inhibit the pollution of the ballast to the power grid, and can instantly reduce the impact of the current on the transistor BG1 and BG2 when the power is switched on, and further improve the power factor.
3. Replace the original triode C2482 with C2258, and the effect is good.
4. After the above improvement, the brightness of the lamp will be reduced. The solution is to remove L2's core, cover it with layers of paper and insert it back in, and watch the brightness change. Repeat several times until the brightness is satisfactory. Finally, seal the magnetic core with wax.