LED strip for car subwoofer

So, I thought it would be nice to try out connecting LED strips in my car, so that they would "pulse" with the audio. After doing some research, I understood that connecting the strip straight to my amplifier would burn the LEDs and might burn my subwoofer or amplifier. So, I decided it would be nice to use arduino and a sound detection module. The problem for me is, I don't know how should I power those LEDs. Is it possible to connect arduino to the amplifier? (Never done anything with arduino, don't judge)

Look into using this chip to detect the audio bands. Power the LEDs from 12V, and have Arduino control N-channel MOSFETs such as AOI514 from digikey.com to control ‘dumb’ LED strips. Car 12V power can have nasty noise spikes on it, be sure to have some protection against that for the power going to the LEDs.

For LED strips with built in controllers (addressable RGB LED strips) using whatever interface is needed to send them bytes of data corresponding to the color for each LED. These are usually 5V powered, so you’ll need a good sized 12V to 5V switching power supply depending on how many LEDs you have.

MSGEQ7 7-band EQ chip.pdf (146 KB)

don't judge

This is an expert forum. Our job is to tell you the truth , the whole truth and nothing but the truth. If you do or did something stupid, it would be our obligation to inform you as such, as that is what experts do. If you want "yes" men, then this is not that place. That being said, we will try to be gentle and try to avoid hurting your feelings, although, truth be told, the only thing that matters here is the facts and feelings should not be part of the discussion. Fair warning, we will tell you what we think, but if it makes you feel any better we will say "very unwise" instead of "stupid". Just so you know, if you were talking to an engineer face to face, and you told him you connected your leds directly to your amplifier, I'm pretty sure he would tell you that was "not very smart". Fortunately, you had the foresight to research it first, so you starting out on the right foot.

This does not call for an arduino. There are standalone little inline devices that are sound sensitive.

INTP:
This does not call for an arduino. There are standalone little inline devices that are sound sensitive.

Could you please give me any examples of such devices?

Could you please give me any examples of such devices?

I can't but I can tell you in general that what they do is detect frequency bands and output a signal, ussually proportional to the amplitude of the center of that band. This is the principle of the 1960s color organs. I built a few. Today you can just buy one of these and it outputs a binary string with the frequency bands embedded . I have no idea how you would interface that chip to a car audio system. I would expect some current limiting resistors would be required to reduce the amplitude to within the chip's range.

"Today you can just buy one of these and it outputs a binary string with the frequency bands embedded ."
Which is the chip I suggested to start with.
It does not output a binary string - it outputs a DC level for the 7 eq bands that the code must read and then acted upon for driving LEDs for example.

"I would expect some current limiting resistors would be required to reduce the amplitude to within the chip's range."
Or more technically correct, a voltage divider circuit to limit the peak voltage levels going into the chip.

You are not really adding anything to the discussion.

If you google "MSGEQ7 library arduino" you will get hits to several libraries, I don't have any experience with any of them.

see bottom of page 1 and 4 on datasheet

It does not output a binary string - it outputs a DC level for the 7 eq bands that the code must read and then acted upon for driving LEDs for example.

I stand corrected. It outputs a series of dc levels where the order of the sequence determines the frequency band.

Tutorial

I got lost there. So what exactly do I need to get the LEDs working?

Maybe you guys are overestimating this guy's ambitions.
He's probably talking about dumb leds and simple sound level detection. Flash to the noise, not a spectrum analyzer.

INTP:
Maybe you guys are overestimating this guy's ambitions.
He's probably talking about dumb leds and simple sound level detection. Flash to the noise, not a spectrum analyzer.

That's exactly what I meant. Lights flashing in sync with the audio. This is something similar to what I want.

Surely you can buy auto color organs online.

@shiftazz, I guess you need to clarify your goal of "connecting LED strips in my car, so that they would "pulse" with the audio".
One group of LEDs pulsing to a specific range of the audio? Pulsing to the overall volume of the audio? Multiple strips reacting to different bands of audio?
You can use the MSGEQ7, just pick off the bassier output, and use that to send a PWM output to a MOSFET to control the brightness of a dumb LED strip.
You can use the Arduino to have the bass output reach a certain level before turning the output up, and change the apparent responsiveness of the strip to the music.
You can make a simple "envelope follower" filter circuit with an op amp or two and just react to the overall volume coming in, and not even need an Arduino.

What is it you want more specifically?

If a simple bar of light is what you're after, just pick up a sound sensitive ccfl kit. Already 12V, use your amp power source, it's a 2 wire hookup. Ccfl has a smoother response curve than leds anyway.

@CrossRoads I was thinking of adding 1 or 2 LED strips so that they would change their brightness depending on how intense the bass is.

@INTP So I googled the ccfl lights and saw that they come in tubes. Are they flexible? If not, it's probably going to be a problem, as I need them to be in a circular shape.

This does not call for an arduino. There are standalone little inline devices that are sound sensitive.

There are some advantages to using a microcontroller...

The [u]LM3916[/u] is a one-chip VU meter, but you'd need to add driver circuits to drive LED strips. (Almost anything will require MOSFET or transistor drivers unless the LED strip has the drivers built-in.)

Or with an op-amp you can make a [u]comparator[/u] that will turn an LED on when the signal crosses a certain level.

The MSGEQ7 requires a microcontroller. (The MSGEQ7 divides the signal into frequency bands so you don't need it if you want if you want the LEDs to respond to the subwoofer signal.)

I've made a few lighting effects with and without a microcontroller. With a microcontroller you can do more "interesting" effects, and it's quicker & easier to experiment with and tweak and change software than to experiment with and change hardware. All of my newer lighting effects have lots of randomly-programmed modes & variations that wouldn't be possible without a "brain".

One "software trick" I use is to take a short-term moving average of the signal and use that to auto-adjust the sensitivity. That way I get good "lighting action" when the volume control is adjusted and with loud & quiet songs. (That can also be done in hardware.)

So, I decided it would be nice to use arduino and a sound detection module.

Rather than a sound detector with a microphone, it's best to tap-into the line-level electrical signal going to the subwoofer amp. However, you do need to [u]bias[/u] the Arduino's analog input because the Arduino can be damaged by the negative half of the AC audio signal (and/or) the signal can be "damaged" (distorted). If you're using a speaker-level signal, you'll probably need a "volume control" and a [u]protection circuit[/u] on the Arduino's input.

It might help if you posted a link for the led strips and posted a photo of the amplifier showing the connectors available.(outputs)

I haven't ordered the LEDs yet, so my choice might change depending on the situation, but I was looking at these. Blue, non-waterproof: LEDs

5050 LEDs are bright. Like, don't look at them directly bright. Especially for your application, you don't need that density either. I would reconsider to something like 3528 LEDs if you're going for a strip.
In general, those strips will be fine. You can cut them to size. Just be aware they are flat strips and won't curve while still facing forward.

INTP:
5050 LEDs are bright. Like, don't look at them directly bright. Especially for your application, you don't need that density either. I would reconsider to something like 3528 LEDs if you're going for a strip.
In general, those strips will be fine. You can cut them to size. Just be aware they are flat strips and won't curve while still facing forward.

Alright, this means I'm going for 3528 LEDs. By the way, somewhere I saw that it is possible to simply put a resistor between the LED string and the amplifier, this would stop the lights from blowing up. Could this be true?