Mutchus

Circuit diagram  Description This circuit is similar to the fading eyes circuit above and is used to slowly brighten and fade interior lights of older cars. The circuit is based around the LM324 low power opamp which draws around 3mA of current, so it won't bother the battery if left connected for extended periods. The top two opamps (pins 1,2,3 and 5,6,7) form a triangle wave oscillator running at about 700Hz while the lower opamp (pins 8,9,10) produces a linear, 5 second ramp, that moves up or down depending on the position of the door switch. The two transistors and associated resistors serve to limit the ramp voltage to slightly more and less than the upper and lower limits of the triangle waveform. These two signals (700 hZ. triangle wave and 5 second ramp) are applied to the inputs of the 4th opamp (pins 12,13,14) that serves as a voltage comparator and generates a varying duty cycle square wave that controls the IRFZ44 MOSFET and lamp brightness. The 5 second fade time can b...

Most cars do not have delayed interior lights. The circuit presented can put this right. It switches the interior lights of a car on and off gradually. This makes it a lot easier, for instance, to find the ignition keyhole when the lights have gone off after the car door has been closed. Since the circuit must be operated by the door switch, a slight intervention in the wiring of this switch is unavoidable. When the car door is opened, the door switch closes the lights circuit to earth. When the door is closed (and the switch is open), transistor T1, whose base is linked to the switch, cuts off T2, so that the interior light remains off. When the switch closes (when the door is opened), the base of T1 is at earth level and the transistor is off. Car Interior Lights Delay  Circuit diagram: Capacitor C1 is charged fairly rapidly via R3 and D1, whereupon T2 comes on so that the interior light is switched on. When the door is closed again, T1 conducts and stops the charging of C1. Howe...