Incandescent lamp life extension switch circuit (2)

Figure 12 is an improved circuit of the above example. The right side of the dotted line is the life extension switch, and the left side is the ordinary lighting circuit
. The bulb E and the switch adopt a two-wire connection method, that is, a single line in and out. It directly replaces the ordinary switch,
and There is no need to change the original indoor wiring.
    When the rising switch S is closed, the 220V alternating current
is rectified by VDl-VD4 and resistor R], causing the bulb E
to be energized and emit light, due to R. The voltage reduction and current limiting effect,
so the lamp E starts to be in a dim light preheating state. Then
the rectified DC pulsating current
charges the capacitor C through VD5 and R. When the voltage across C rises to
about 0.7V, the one-way thyristor VT is turned on,
the resistor R is short-circuited, and the lamp E is "fully bright" and
normal. glow. Since the gate of VT is connected with a large capacitor C, VT will not turn off after it is triggered and turned on until
the switch S is turned off.