Photoresistance controlled twilight switch - has circuit with four NAND=gates connected to transistor with collector connected to triac

摘要

The lighting up or twilight switch based on the main patent has a voltage divider circuit with a fixed resistance (52) in series with a variable resistance and the photo resistance. This is interconnected with a delay circuit with two capacitors across the power supply. The junction of the capacitors is connected to the junction of the first two gates by a resistance. The output of the last gate is connected by a resistance to a transistor with its collector connected to a triac. The lighting system is thus switched in or our depending on the resistance of the photo resistance.