Courtesy light delay

courtesy light delay 87 Ever been groping about for the safety belt, ignition slot, choke con- trol or a map while in utter darkness and happy to have closed the car door(s) because of the cold, or foul weather? Wouldn"t it be convenient to have the courtesy light on for a few more instants in order to get the ve- hicle started and ready to move off? Figure 1 shows a courtesy light delay circuit for easy incorporation in almost any type of car. The courtesy light is switched by power MOSFET T2, which is a Type BUZ72A ensuring a low voltage drop (0.2 V typ.) across drain and source and therefore the lowest possible power loss. The door contact, connected to terminals B and C, is normally a push to break type. T1 is therefore off and C1 discharged when the door is closed; MOSFET T2 does not conduct, so that the courtesy light remains quenched. Opening the door, how- ever, causes T1 to charge Cl, and the courtesy bulb will therefore light in a gradual manner. Although closing the doo...