Anyone good with electrical circuits?

So I am working on a “Because I Can” project. I am building a portable radio out of car stereo equipment. This isn’t the first one of these I have done but it will be the first where I cut the box with the X Carve. I am not having any issues with that, however I wanted to jazz this one up a bit. I have some LEDs I want to attach to the outside of the box and have them pulse with the music. The problem I have is that I am an amateur at best when it comes to wiring circuits such as this from scratch. I need to figure out what components I need to achieve my desired result without starting a fire or blowing out my LEDs. I am using a 13.8 volt 34 Amp switching power supply and a Sony head unit. I know I am going to need resistors to bring the power supply voltage down to 12 and a MOSFET that will use the current from the sub channel to switch the main power from the power supply to the LEDs on and off. I’m just a little shaky on how these components should be wired and if I need anything else for the circuit. I figure I have gotten great advice from the community so far, why not ask you all. Any advice would be greatly appreciated.

You can do some really cool stuff with an Arduino, some WS2812B LEDs (also called Neopixel), and not much else. Since you assembled your X-Carve you’ve already touched an Arduino. The connections are quite simple, you can hang a whole string of the LEDs off one pin of the Arduino, connect the line level audio source to an analog input pin on the Arduino, and basically hook power.

Here’s an Instructable link
Here’s a demo of something similar

@RobertCanning I started a while ago with Google and found several wiring schematics. My main issue was they were all vastly different and were suppose to all do the same thing. One was as simple as a voltage resistor and a MOSFET and another looked like this

I’m not an electrical expert but having two circuits, one that simple and one that complex that do the same thing doesn’t seem quite right to me. Maybe I am wrong but would rather be safe than sorry.

@StevePrior I thought about using an Arduino as I wouldn’t have any issues setting that up but when I thought about it I ran in to three problems that mostly exclude the Arduino solution. One is I can’t really get line audio to pass through the Arduino and back to the car speaker, or at least I haven’t figured out how to, reliably without killing audio quality or frying the Arduino. Second is I am worried that the sealed box construction will damage the Arduino board over time from the force of the compression created by the speaker cones. I actually have one of these I built with four speakers and I blew out two of them because I failed to properly seperate the front and rear chambers. Third is size constraints. The Arduino isn’t big but the box for this radio needs to fit inside a three segment locker so I need to keep as much room inside it as I can. This is mostly why after reading that it can be done, I chose to try a simple circuit.

I was looking at that one. I just need to figure out how to pull the audio without using the 3.5mm jack.

I would use a ground loop isolator to prevent noise from coming into the audio

This should give you some ideas