fade fade out led circuit car interior lighting

Posted on Feb 7, 2014

LED`s lining the headliner, and have them fade in when the door is opened, fade out when the door is closed. I think it should be simple. from what i gather i`m going to need: i don`t really know. basically i need to know what circuits will be necessary to use 12v power from the vehicle to illuminate 15 leds, and fade them in/out when the doors are opened/closed He can use the 555 as a PWM driver into a Power

fade fade out led circuit car interior lighting
Click here to download the full size of the above Circuit.

MOSFET into a Capacitor with the load acting as the R component in the RC Charge pump. Thus the duty cycle of the 555 governs the voltage seen by the load and controls the brightness via a potentiometer. the fade out seemed to me like it could be done with a 555 monostable using a capacitor between the output and the LEDs, thus the door closes, a 5 second delay, then the 555 output goes low, and the cap discharges to dim the lights But to entertain the other thoughts, you may not need linear dimming. e. g. The voltage across a capacitor might be able to contol a voltage to PWM converter. Velleman makes a voltage to PWM circuit board. So, I`m thinking. When the door opens apply full voltage to the PWM thingy. (Actually it has a slow start feature) and apply a buffered output of the voltage across the capacitor from a RC circuit. You probably will have to power the RC circuit from the always on circuit. What I`m thinking of is somthing that could charge a cap when the door is open and remove the charging source and connect a resistor in parallel when the door closes. Use the buffered voltage acroos the cap to drive the PWM thingy. I think quiesent currents will get in the way. e. g. the current drain on the battery when the car is off. Maybe just a simple RC on the gate of a mosfet will do the trick. The mosfet will dissipate a bit of heat during the ramp up/down, so if it gets hotter than you`d like, put in on a heatsink...

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