LEDs linked to car radio?

Discussion in 'The Projects Forum' started by ndogg34, Mar 19, 2010.

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  1. ndogg34

    Thread Starter New Member

    Mar 19, 2010
    So I'm redesigning the interior of my car, and part of the project is going to involve LEDs linked to the stereo to "pulse" with the music. Based on what I've read, I'm assuming I would be attaching a three port switch (to allow for off, on, and "pulse"). The "On" position would simply connect to the "LED" portion of the circuit (parallel circuits each consisting of a resistor and LED), whereas the "Pulse" position would connect to the emitter of a transistor and the "bottom" of a rectifier. The collector of the transistor would also connect to the "LED" portion of the circuit, and the base would be connected to the "top" of the rectifier. The radio outputs would be connected to the "sides" of the rectifier.

    According to the manufacturer's details, the line output is 1.5 Vrms. Taking that, along with the fact that LEDs I'm looking at are rated for 2-4V and 20mA, a 12V car battery, I should be able to calculate the size of the resistors needed to make everything work. I'll need to play around a bit, as I would like the intensity of the LEDs to vary with the intensity of the music, so the max voltage would need to yield around 16mA, while the threshold voltage could yield around 2mA....

    This is just my uneducated take on it.. am I way off base? Is there anything I've missed, or something I need to be careful of? Any help would be greatly appreciated.


  2. beenthere

    Retired Moderator

    Apr 20, 2004
    Flashing lights inside the car can't be anything but a major distraction. They may also be illegal. We can't help with this.
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