Stepless dimmer fluorescent lamp circuit

The stepless dimming mouth light circuit can be found on the website 54. It
consists of two major parts: a skin adjustment circuit, a high-frequency oscillator and a filament transformer.
    T] is the filament transformer, the power switch s on the stage, and its secondary winding N. , M can output 7-8V AC
voltage and add it to the filament at the end of the fluorescent tube to preheat it and emit electrons. VT1 and T2 form an inductive feedback
high-frequency oscillator. Its DC power supply is obtained by N: The output AC voltage is obtained by VD1 half-wave rectification and (1. filtering).
The oscillation frequency is about 15-20kHz, and the oscillation voltage is boosted by T2. N. Output (peak voltage ≥ 400V)
and add it to both ends of the fluorescent tube through G, causing the lamp gas to quickly ionize and light up. Since the lamp transformer
always supplies a certain voltage, the filament maintains the ability to emit electrons, even if the fluorescent tube When the working current is small,
both ends of the lamp are not easy to turn black.
    The voltage circuit is composed of a bidirectional thyristor VTH, a bidirectional trigger diode VDH and a zinc resistor phase shift circuit.
By adjusting the potentiometer RP, the conduction angle of the thyristor VTH can be changed . The power frequency alternating
current added to both ends of the fluorescent lamp changes, thereby achieving the dimming effect of changing the luminous brightness of the fluorescent lamp.
    VT1 requires the use of 3AXSIB type and other germanium medium power transistors, p≥60, Z. The smaller the better. VTH uses
1A/600V bidirectional thyristor, such as MAC97A6 type, etc. j, which is a ballast matched with the lamp. The filament
transformer Tl can use an El-type silicon steel sheet with a core cross-sectional area of ​​1,mm×17mni, ~ times The winding N
is wound with 3890 turns of imm high-strength polyester enameled wire, and the secondary winding ~, N is wound with 126 turns of 35mm high-strength
polyester enameled wire. The core of high-frequency transformer T2 can be MX-2000 type 1; .6 Ferrite, winding
N. and Nj are wound with 12 turns and 36 turns respectively with ≠0 35mm high-strength polyester enameled wire, IV. Use
1700 turns with ≠0 imm high-strength polyester enameled wire.
  This circuit uses high-frequency voltage Therefore, the fluorescent lamp has good shoulder motion performance and
can light up quickly at an ambient temperature of 15 to 60°C. At the same time, the power frequency AC voltage and high frequency AC voltage output by the bidirectional thyristor control
are superimposed . , added to both ends of the daylight guide tube, can adjust the light brightness smoothly and effectively prevent the light
from flickering.