Electronic design of NE555 switch power socket

　　Multi-purpose delay switch power socket

　　The power of household appliances, lighting lamps, etc. often needs to be turned on or off after different time delays. The power socket can meet such different needs.

　　working principle:

　　The circuit is shown in the figure. It consists of voltage reduction, rectification, filtering and delay control circuits. Press AN, 12V working voltage is added to the delayer. At this time, the 2nd and 6th pins of NE555 are high level, and the 3rd pin output of NE555 is low level, so relay K is powered and works, and contact K1-1 is pulled upward. At this time, the "delayed closing" socket is powered, and the "delayed opening" socket is not powered. At this time, the power supply passes through capacitor C3, potentiometer RP, and resistor R3 to "ground" to charge C3. As the voltage on C3 increases, the voltage of 2nd and 6th pins of NE555 decreases more and more. When this voltage drops to 2/3Vcc, the output of 3rd pin of NE555 jumps from low level to high level. At this time, the relay will lose power and not work, and its control contact will return to its original position, then the "delayed closing" socket loses power, and the "delayed opening" socket is powered. In this way, different needs are met, and LED and LED2 make corresponding indications.

　　This circuit can work normally as long as the components are good and assembled correctly.

　　The delay time is determined by the value of C3 and PR+R3, T≈1.1C3 (PR+R3). RP refers to the effective part. C3 can use a capacitor ranging from tens of pF to 1000μF, and the value of (PR+R3) can be 2K~10MΩ. The withstand voltage of C1 should be ≥400V, the power of R1 should be ≥2W, the AN button switch can be K-18 type, and the relay model is JQX-13F-12V. There are no special requirements for other components.