Simple light-controlled street light circuit (1)

A simple and easy-to-make light-controlled street light circuit, as long as night falls, the lights will light up automatically, and during
the day, the lights will go out by themselves.
    The thyristor VT constitutes the main circuit of the lamp E, and the control circuit
is composed of a voltage divider composed of a two-plate tube VD, a resistor ruler and RTL. The function of VD is to
provide DC power for the control circuit. During the day, when the natural light is strong, the photoresistor RL
shows low resistance. As a result of its voltage division with the ruler, the gate of VT is at a low level,
wr is turned off, and the light E is dimly lit. When night falls, the natural light shining on RL
is weaker than RI. It shows high resistance, so the gate of VT is at a high level, VT
obtains the positive trigger voltage and turns on, and the lamp E lights up. Changing the resistance of R
will change the voltage dividing ratio between it and RL, so the starting control point of the circuit can be adjusted so that the lamp
will not start to light up under the appropriate illumination.
    Another feature of this electric shoe is that it has a soft shoulder function. Because when night falls, the natural light gradually
becomes weaker, so the photoresistor Rl. The value of m is gradually increasing, and the VT gate level is also gradually increasing. Therefore,
the thyristor changes from the off state to the on state through a micro-conduction and weak conduction stage, so the lamp E has a
soft-start process that gradually becomes brighter. When VT is fully turned on, the current flowing through the lamp is half-wave alternating current, that is, the
lamp is in an under-voltage operating state. These two factors are extremely beneficial to extending the service life of the bulb, so this circuit is very suitable for use as
street lights in residential areas, eliminating the trouble of frequent replacement of bulbs. When installing, pay attention to RI. It is not
illuminated by the light of lamp E itself.