在黑暗的停车场停车时,一旦车门关上,由于车内灯光立即熄灭,会使司机找不到车门锁孔而难以锁车。本电路可使车内灯光逐渐变暗直到锁好车门为止。晶体管Tr2驱动车灯,本身受脉宽调制器3524驱动。车门打开时,车门开关闭合,C3全部放电, Parking in the dark parking lot, once the door closed, due to the car lights immediately extinguished, the driver can not find the door keyhole and difficult to lock. This circuit can make the car light gradually dim until the door is locked. The transistor Tr2 drives the lamp, itself driven by the pulse width modulator 3524. When the door is open, the door switch is closed, C3 is fully discharged,