How to control 12v light strips to match music beat.

[Mint.]

So I have a strip of 12v LED lights, 4 strips each requiring 0.7W. How would I go about putting some music into some circuit and the lights would flash along with the beat of the music?

[Gall]

The simpliest circuit I know is like that:



It comes from 1960's. Depending on the voltage and the transistors, it works either with single LEDs, LED strips or incadescent lamps. It is possible to use Darlington transistors or triacs.

Three channels correspond to bass, mid and treble. Since you have only one strip, just use only one channel - the bottom one (bass).

[Mint.]

The simpliest circuit I know is like that:



It comes from 1960's. Depending on the voltage and the transistors, it works either with single LEDs, LED strips or incadescent lamps. It is possible to use Darlington transistors or triacs.

Three channels correspond to bass, mid and treble. Since you have only one strip, just use only one channel - the bottom one (bass).

Can you please give me the link for that schematic, I can't find it anywhere on their website.

[Uncle Vernon]

Alternatively purchase October edition of Silicon Chip magazine. I believe they are running a LED upgrade of their Musicolour.

[krish2487]

Alternatively

Music Source --> Bandpass Filter 1 --> 10 step led bar graph using 3914
                            Bandpass Filter 2 --> 10 step led bar graph using 3914
                            Bandpass Filter 3 --> 10 step led bar graph using 3914
                            Bandpass Filter 4 --> 10 step led bar graph using 3914

design the filter  to pass the frequency you want to display.
the 10 step led bargraph thingy dave covered in one of his videos
(brilliant tutorial for newbies like me... :-D)

i am assuming that the strips are of 3 leds each with their own current limiting resistor
(that is a standard led strip anyway)

you have your own 4 channel graphic equalizer display
:-)

[tomilepp]

For more complex method you could use PC to analyze music and AVR micro to drive LEDs, like in my project:
http://code.google.com/p/avr-rgbled/

It has beat detector running in PC (taken from http://bear24rw.blogspot.com/2011/08/rgb-led-coffee-table.html) which talks via USB to ATmega32U2 and it drives 4 RGB led strips.

[mtkaalund]

or you could go the full monty and implement an FFT in a microcontroller or an FPGA/CPLD, and use that

[IanB]

Hey guys, let's be real here. The OP isn't going to be designing band pass filters or programming FFTs. He's still in high school and hasn't yet completed 11th/12th grade mathematics and physics classes.

What he needs is an example circuit with a list of parts and clear instructions on how to build it. Something like the link Gall posted.

[Mint.]

Well yes somewhat. What I got in mind is so:

Input of audio signal --> filters --> audio amplification to set level --> audio turns on the transistor which drives the LED's.

In the case of the audio amplifier, is it possible to amplify a signal to a specific level and not exceed for example more than 100mV?

But besides all that, I feel confident about this project, but in saying that I haven't actually started prototyping it so I am not even sure it will work!

[T4P]

Use a inverting opamp as i read that they can push 2VP-P max at 1kohms
So attentuate that by 20 times, i assume you know how to make a inverting opamp stage right?

[bombledmonk]

I remember seeing this in wired magazine.  It's not a particularly great choice on parts, but it does do pretty much what you are looking for.

http://dkc1.digikey.com/us/en/mkt/pulse.html