Incandescent lamp life extension switch circuit (5)

It is an incandescent spider life-extending switch with another connection method. It has two major functions: first,
it can start at half voltage reduction when the power is first passed, and then switch to full voltage power supply after the filament is fully warmed up; second, once the power supply is on the market, When the power grid voltage
is higher than the standard value of 220V...about 20V, the circuit can automatically switch to half-wave step-down power supply, which can effectively extend
the life of the K incandescent lamp.
    After closing the switch S, when the alternating current is II-half cycle
At this time, the power supply seeks power through Vn1, R, and VD2 to the capacitor (Vn1, R, VD2)
. (The voltage I at both ends gradually increases, but is far lower than
the rJ limit voltage of the voltage regulator tube vs. vs is in the cut-off state, and
the thyristor VTH has no trigger current. In the off state,
the photocurrent of bulb E flows. When the alternating current is in the negative
half cycle, the current passes through VD3 and R, providing
a negative pole contact pull current to VTH, causing VTH to turn on, and
bulb I: half is switched. The current flows through E for preheating. As long as
the voltage across C is less than the vS regulated voltage I, in one
cycle of AC power, the current flowing through E is only half a cycle, which is the soft start process of the light bulb. As time
goes by , The voltage at both ends of r continues to rise. When it rises to and exceeds the regulated voltage value of vs, VD2 is reverse-biased and cut off, so vs is turned on. The power supply supplies trigger current
to VTH through VD1 and R. Therefore, the alternating current is in the positive half cycle and VTH is also turned on. At this time, F enters the full voltage power supply state. The soft start time of this circuit is mainly determined by the capacitance of the capacitor (1).     If the grid voltage suddenly rises and exceeds the value not calculated by the circuit, the base sampling voltage of the transistor VT1 will increase. , the original cut-off state of wri mountain flips to the on state. At this time (, the stored charge will be discharged to VT1, vs returns to cut-off, and the circuit returns to the original, r-wave power supply state.     Try: disconnect first After VD2 is turned on r S, E should stop glowing normally. Then turn on VD2, and rotate the driving end of RP to the ground end, so that VT1 enters the cut-off state. At this time, when power is turned on, you can observe the soft start of E first darkening and then brightening. If the soft and flat moving time does not meet the requirements during process t, you can adjust the capacity of C. Then connect the circuit to the output , adjust the voltage to about 2-10V, and finely adjust RP with a small screwdriver to make VT1 just right. Cut off, that is, observe that the bulb F suddenly changes from bright to dark.