Car cab based on 555 delay lighting

Car Audio Crystal 3.2*2.5mm 3225 24M (24.000MHZ) 20PF 10PPM 20PPM 30PPM

When the door is opened, the liquid touch switch SA1 is closed, and the illumination lamp EL1 is illuminated. At this time, the timing capacitor C1 is discharged through the closed contacts of D2, R1, and SAl. When the door is closed, the contact of switch SA1 is released, at which time the voltage on C1 is lower than 1/3 of the supply voltage. The 555 integrated circuit output terminal 3 is high level, VTI-VT3 is turned on, and the illumination lamp EL1 is kept on. Capacitor C1 is charged by D1, VT3, R3. Before the charging voltage on capacitor C1 is set to 2/3 of 555 supply voltage, 555 circuit output is still high level, VTl-VT3 remains in conduction state, and the lamp is in delay. When it is lit, when the voltage on Cl is charged to the 2/3 555 supply voltage, its output becomes low and ELl goes out. The delay time of this circuit depends on R3, C1, and the circuit delay is 10-15 seconds.