Ceiling light lighting circuit

(1) Circuit composition The chandelier control circuit consists of a power supply circuit and a trigger control circuit, as shown in the figure.
    The lamp is a circular fluorescent tube produced in Guangdong. The model is NTA-Y21X, the rated voltage is AC220V, and the input power is 21W. Draw
the circuit diagram of the lamp according to the actual object for reference.
  Working Principle: After powering on, the 220V alternating current is rectified by bridge VD1~VD.4 and filtered by capacitors cl and Cz (each capacitor of Ci and C2 is charged with
a DC voltage of about 155V, and the superimposed voltage of cI and G in series is about 310V). Since the voltage at both ends is zero when G is powered on, the 310V voltage is applied to
the ce pole of VT2, and current flows through Shu and the b and e poles of VT2, and VT2 turns on quickly. At this time, the current flowing through the filament at both ends of the lamp tube, C6, inductor
L and the ① to ② end windings of the high-frequency transformer T continues to increase, and an electromotive force is induced at the ① and ② ends of T (① end +, ② end - ),
hindering the increase of current} ③, ④ terminals induce electromotive force (③ terminal +.@ terminal one). Charging C' increases the base current of VT2, and VT2 quickly
enters saturated conduction. At the same time, the ⑤ and @ terminals should produce electromotive force (⑤ terminal +, ⑥ terminal 1), which reversely charges C. VT1 is cut off due to reverse bias
.
    When the current at terminals ① and ② increases to the maximum, the induced electromotive force at terminals ③, ④ and terminal ⑤, @ disappears. At this time, due to the discharge of the C3 and C4 capacitors
, VT1 changes from off to on, VT2 changes from on to off, and the current flowing through the ①~② windings quickly reduces to zero. Then,
the current flowing out from the positive electrode of C1 flows into the e_e electrode of VT1, the ②-① winding, the inductor L, the filament and C at both ends of the lamp tube, and flows into the negative electrode of Ci. When the current flowing through the ①-②
winding decreases rapidly and reverses While increasing in the direction, terminals ① and ② induce reverse induced electromotive force (terminal ②+, terminal ①-), which hinders
the decrease of forward current and the increase of reverse current. Electromotive force is induced at terminals ③ and ④ (④ terminal +. ③ terminal one), so that the voltage originally charged by G (left terminal +,
right terminal one) is superimposed, making VT2 more cut off and quickly charging G in the reverse direction: and terminals ⑤ and ⑧ also induce reverse electromotive force, which is the same as the original voltage of 6 The charged
reverse voltages are superimposed, causing VT1 to quickly saturate and conduct and quickly charge G forward. The reverse current flowing through the ①~② windings quickly increases
to the maximum. The induced electromotive force disappears at terminals ① and ②, terminals ③ and ④, and terminals ⑤ and ⑥. At this time, due to the discharge of the G and 0 capacitors, VT
changes from conduction to cutoff, and VT2 changes from cutoff to conduction.
    This goes on. vri and VT2 are turned on and off over and over again (G and G are repeatedly charged forward and reversely charged). The current flowing through
the filament and C6 at both ends of the lamp is high AC. After several cycles, the filaments at both ends of the lamp are heated and emit electrons. The high voltage to the lamp, which ionizes the gas in the lamp and conducts it. At this time, a high amount of alternating current flows through the lamp. Make the tube glow. The appearance and circuit are shown in Figure 16-24, '