Dome Light Dimmer

Cars, Electronics

I have been try­ing to repli­cate the inte­ri­or light func­tions of some of the new­er cars for some time now. I like how they stay on after the door is closed and then fade away. This is also called the­ater light­ing.

This cir­cuit is based around the ever use­full 555 timer, and an N chan­nel MOSFET.

I am build­ing this for my 1969 Chev­elle. Dako­ta Dig­i­tal has some­thing sim­i­lar, but I didn’t want to spend $200 on it. I am work­ing on repli­cat­ing the retained acces­so­ry pow­er too.

Here is the cir­cuit on a pro­to­typ­ing bread­board.

The capac­i­tor (C2) & resis­tor (R4) con­nect­ed to pins 6 & 7 on the 555 timer con­trols how long the out­put on pin 3 is high. A larg­er capac­i­tor or more resis­tance will give you more time.

The fade effect comes from capac­i­tor (C1) and resis­tor (R1), which pulls the volt­age down slow­ly.

Dome Light Delay / Dim­mer v3 Schemat­ic

  • K1: Switch­es on the doors con­nect­ing the trig­ger to ground.
  • K2: Igni­tion switch to can­cel the cir­cuit — turn lights off imme­di­ate­ly, unless doors are open.
  • Q1: 2N7000 MOSFET
  • Q2: NPN 2222 Tran­sis­tor
  • U1: 555 Timer
  • C1: 22uF Capac­i­tor
  • C2: 100uF Capac­i­tor
  • C3: .02uF Ceram­ic Disc Capac­i­tor
  • R1: 447K Ohm 1/4 Watt Resis­tor
  • R2: 1K Ohm 1/4 Watt Resis­tor
  • R3: 1K Ohm 1/4 Watt Resis­tor
  • R4: 10K Ohm 1/4 Watt Resis­tor
  • R5: 1M Ohm 1/4 Watt Resis­tor
  • R6: 1K Ohm 1/4 Watt Resis­tor
  • D1: 1N914 Diode
  • D2: 1N914 Diode