Full color LED's sync to music

[arthur106]

I know almost nothing about electronics, I know about basic electric theory as I just completed AP Physics, but when it comes to designing useful circuits, I'm a noob.
I want to have some full color LED's in my car that will vary in brightness depending on the volume of the music. They will come on at a certain volume and get brighter as the music gets louder.
I figure that the three bases of the LED's (red, blue, green) can each be controlled by a potentiometer or variable resistor. That way, by twisting three knobs, I can choose any color I want for the LED's. (I guess they will have to be in series with a resistor and transistor so that I will have the option of turning each color completely on or off).
To make the lights sync with the music, I think I will have to use RCA output to control the amount of current from my 12V car battery that will power the lights. (I have to RCA outputs that are unused, and I don't want to rip my doors off to get to the speakers, so either RCA or a 3.55mm audio jack are my only options). How should I go about using the RCA output to control the amount current that goes into the lights from the car battery?
What do y'all think about this? Any ideas to make it better? Is there any possibility that I will end up turning my car into a giant ball of fire?
Any help would be greatly appreciated!

 

[Mosaic]

U can't adjust the intensity of the RGB elements with a linear control very well. I suggest you drive each with pulse width modulation. You can achieve PWM using a 555 timer for each of the RGB elements. Frequencies need to be > 100Hz for smooth operation.

This should work as is.

**broken link removed**

In the example shown, you won't need the FET power driver as the 555 can direct drive any LED.

BTW: this only provides color/intensity control.

To make it sync with your RCA out or pwr amp out you will need to influence the PWM cycle with the audio signal. In effect modulate it.

Perhaps the simplest way is to have the output of the 555 drive the emitter of a transistor (npn) and supply the base signal to the transistor via a 1kohm pot. tied between the audio signal and ground with the centre tap feeding the base via a 1k resistor. The collector of the transistor drives the cathode of the LED. LED would have to be a com. anode type here.

 

[audioguru]

Since you don't know what you are doing then you might set your car on fire.
Get a friend who knows about electronics to make a "color-organ" kit for your car. Have a car radio installer connect it.