Light controlled lighting using one-way thyristor

RG is a photoresistor, which forms a voltage divider with the fixed resistor R. Its divided voltage value is rectified
by the diode VD and added to the gate of the thyristor vs as the trigger voltage. During the day, RG is exposed to indoor natural light and shows low resistance, and the partial voltage value is low, which is not enough to trigger the thyristor vs. Therefore, vs is in the off state and the lamp H does not light up. When night falls , RG has high resistance without light exposure, and its partial voltage value is relatively high. After being rectified by VD , it is added to the door panel of vs, so that the lamp H is turned on quickly and the lamp H lights up. When the lamp is in the glowing state, the current flowing through it is half-wave alternating current, and the lamp is in an under-voltage state, so the service life of the lamp is extremely long. Therefore, this circuit is very suitable for unmanned public walkway lighting.