Incandescent lamp life extension electronic controller (2)

The high-power field effect transistor VT, resistors Rl and R2, and capacitor C form a circuit that limits the starting current . Since VT must
operate normally under direct current, a bridge rectifier circuit is composed of diodes VD1-VD4, which
converts 220V AC power into DC pulsating voltage , which is then used for VT work. Close switch S. Since the voltage across the capacitor C is zero and cannot change suddenly,
VT is in a cut-off state and the lamp H cannot light up immediately. over time. C is gradually charged to voltage through Rl
, and VT also changes from the cut-off state to the saturated state through the amplification area. The current of its drain D gradually increases from zero to the
rated , thus avoiding the moment when the light is turned on. The cold resistance of the filament is very small, which causes a strong current to impact the filament, causing the power supply
voltage to slowly increase to both ends of the bulb as the filament temperature gradually increases.