Automotive dome light delay dimmer

There are two phases: the first is a delay phase, and the second is a fade-out phase. When you open the car door, the light comes on. You get into the car and close the door, but the light stays on (delay phase) for an adjustable time (0-40 seconds depending on the value in the circuit, but you can easily adjust it, for example, by using a larger capacitor), so you can see where you insert the key or do whatever you did when you got into the car, and then fades out at an adjustable speed (fade-out phase). If you connect the ACC line (which is entirely optional), when you turn the key to the ACC position, the light turns off (effectively fades out), even if the delay phase hasn't ended yet (it cancels the delay phase).

The SR1 trimmer potentiometer adjusts the delay time (the period when the bulb is at full intensity), and you have an "indicator" LED that illuminates during the delay phase; this allows you to visually set it to any duration you prefer. When the first phase ends (marked by the LED no longer being lit), it enters the second phase – fade-out. The SR2 trimmer potentiometer adjusts the fade-out time (or, if you prefer, the speed). The diagram above illustrates how the dome light switch is typically connected (the connection may vary depending on your car brand and model, in which case you'll have to figure it out yourself).