LEDs flashing in time to music / modifying a "car music

Brucebruce · Post by **Brucebruce** » Thu Oct 15, 2015 8:37 am

Hi all,

I'm struggling with something. I want to have a set of different coloured LEDs flash in time to music. I looked into various ways of doing this but since my electronics knowledge is pretty much limited to hooking up LEDs in simple circuits, a lot of the ways seemed very complicated. I also looked at arduino but couldn't find a way for it to run from the board and not from my laptop (with the arduino connected).

I then came across this on ebay:

http://i.imgur.com/PFlmFsz.jpg

It plugs into the car cigarette lighter, so is 12 volts. It has a grill with a mic behind it which listens for music and lights up this strip of LED's accordingly:

http://i.imgur.com/PUY6ffv.jpg

My plan, initially, was to bypass the internal mic by opening up the box, cutting off the mic and soldering a connection to the output line from my mp3 decoder. This seemed to either break the mp3 decoder or amp (they both still turn on but the music plays in stutters). I gave up on this idea and decided I would just keep it as listening as the speaker will be mounted right next to this. Here's what the inside looks like btw (This the one where I've removed the mic).

http://i.imgur.com/KkRtfUP.jpg

So I cut the wires that attach to the LED strip:

http://i.imgur.com/s4Tv7MW.jpg

and began using a small LED strip to test which were positives and which were negative. I found this out and found that some of the wires would light the LED strip with higher pitched nosies and others would light them with more bass noises. (Much funny looks from my wife as I groaned and whistled at a little box).

I then set up 4 white leds hooked together, 4 blue leds hooked together and 4 green leds hooked together. I tried to then attach the wires from the box to get it to light up. My white leds stopped working but I assumed it was just my fault. Now when I try the different wires with an led strip it seems to break the led strip. The lights come on, flicker, then the strip stops working.

I'm guessing it's maybe frying them but I'm not sure how as the strips are made to handle 12v and I'm only putting 12v in!

I've probably explained this all very poorly but if anyone has any ideas of where I'm going wrong I'd be very grateful!

Kylwell · Post by **Kylwell** » Thu Oct 15, 2015 11:48 am

Sound to light converters have been around since... well before electronics actually. I used to have one that wired into a speaker output for pulsing lights. Sounds like you're on the right track but w/o being able to fiddle with the parts I'm useless as a troubleshooter. Have you tried http://www.instructables.com/id/Sound-T ... Converter/

Mr. Engineer · Post by **Mr. Engineer** » Fri Oct 16, 2015 1:07 am

Not sure about this but on the second picture, the 'LEDs' looks more like Electroluminescents, which runs on AC and not DC

There are other sound to light circuits, such as the infamous LM3916 UV meter IC. I ma sure there is even a kit for that as well.

Here is a quick Google Search:
https://www.google.com/search?q=lm3916+ ... OOCh3lVQPa

Brucebruce · Post by **Brucebruce** » Mon Oct 19, 2015 12:06 pm

Since posting this I've read and read and read and basically I'm not further forward :S hehe.

I don't know the basics of electronics theory so things like circuit diagrams are fairly meaningless to me.

I found this:

http://www.instructables.com/id/How-to- ... /?ALLSTEPS

Could anyone please take a look at it and tell me if, the audio input is fine to be from an mp3 decoder and not from a microphone/headphone jack?

I think maybe the voltage from an mp3 decoder and headphone jack is different and could end up blowing the amp on the mp3 decoder? (Like what happened when I tried just using a tip31 transistor in a circuit that I later found out was very flawed!).