One of the fluorescent lamp dimming circuits

The brightness adjustment of fluorescent lamps cannot be achieved by using a general voltage regulating circuit
. Otherwise, as the voltage at both ends of the lamp decreases,
the filament temperature also decreases, and the fluorescent lamp will not be able to start. Therefore
, the brightness adjustment of fluorescent lamps should be able to
reduce the current of the lamp tube without reducing the electron emission intensity of the filament.
(1) One of the fluorescent lamp dimming circuits
    is shown in Figure 2-78. It utilizes capacitive dimming circuitry . The switch S1 contact of the Ne circuit of the string starter is
set to prevent the lamp from starting to light up when there is a capacitor in the series, thereby extending the service life of the lamp. For two-level dimming,
use a capacitor Cl. For three-level dimming, use two capacitors C1
and island, and connect a switch sz in the C2: loop. The actual effects of capacitor dimming of
    fluorescent lamps are listed in Table 2-1.