Electronic starter for fluorescent lamps with magnetic ballast

At present, there is still a serious low voltage phenomenon at night in remote areas, which makes it difficult for users who use inductive rectifier fluorescent lamps to turn on. Although changing the inductive ballast to an electronic ballast can make the lamp bright immediately, it is not economical. According to the author's many years of maintenance experience, users who use electronic ballasts generally need to replace a lamp tube every 3-5 months, while users who use inductive ballasts only need to replace a lamp tube every 4-6 years. After calculation, using electronic ballasts is indeed energy-saving but not cost-saving.

The author has made an electronic starting circuit that can light up fluorescent lamps even at low voltages. It is extremely easy to use and not only lights up right away, but also extends the life of the lamp.

The circuit is shown in the figure. The circuit is a delay circuit composed of NE555, RP and C3 to control the delayed disconnection of the relay to realize forced start and light up the fluorescent lamp a few seconds after the light is turned on. Among them, R and C1 are connected in parallel to reduce the voltage. After the mains voltage is reduced, it is rectified by VD1~VD4 bridge and filtered by C2 as the working power supply of NE555. After the switch S is closed, since the voltage across C3 is zero, the (2) and (6) pins of NE555 are low level, and the (3) pin outputs a high level to make the relay K close. At this time, the fluorescent lamp filament is powered on and preheated for ignition. At the same time, the power supply charges C3 through RP. After a delay of several seconds by R and C, the (2) and (6) pins are high level, NE555 flips, and the (3) pin outputs a low level. The relay K loses power and the mercury vapor of the fluorescent lamp is powered on to emit light.

R can use a 420kΩ 1/8W carbon film resistor; C1 can use a 0.047μF polyester capacitor with a withstand voltage of more than 630V; C2 and C3 can use 150μF and 22μF electrolytic capacitors respectively; C4 can use a 0.01μF ceramic capacitor; RP can use a 100kΩ potentiometer; and the relay can use a 9V DC relay. The entire circuit can be installed on a 4cm×6cm copper-clad board. Adjust RP according to the voltage fluctuation in the local area to determine the start delay time. After installation, seal it with tape and place it in the fluorescent lamp holder. It is ready once installed.