# Need Help!

Discussion in 'The Projects Forum' started by blink1, Sep 9, 2012.

Sep 9, 2012
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Hi guys.

Let me start off by saying what I would like to do.

My goal is to get LED strips and put them around the perimeter of my dorm room (its probably around 12x14 feet or somewhere around there), and have these lights flash to the music coming from my computer.

I have been doing my research and looking for some type of module or piece of hardware that I could plug into the wall, plug the lights into, and run a cord from my computer to this device so that it knows when to pulse the lights with the bass of the music.

Unfortunately, I have no experience with any of this yet and would really like some help. I have seen people on the internet with LED organs.... is that the way to go? Or is there a simpler device that would do what I am looking for. I am assuming it will be costly seeing as there will be allooooot of lights going up.

Links to products/ and or explanations as if i was in elementary school would be much appreciated!!! THANKS

Aug 21, 2008
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Sep 9, 2012
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4. ### Austin Clark Active Member

Dec 28, 2011
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Are you strictly interested in purchasing such a device? Or are you up for some building?

As for a commercial device, I'm sure a quick Google search can get you somewhere, but on the top of my head I wouldn't know. As for a potential build, first are you wanting super-bright LEDs like in the videos, or would you be ok with the smaller christmas-like LEDs?

Apr 30, 2011
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Velleman MK186 (kit) or VM186 (assembled).

http://www.vellemanusa.com/products/view/?id=525680

http://www.vellemanusa.com/products/view/?id=525686

You can alter the frequency response to make the circuit more responsive to bass and less responsive to treble by changing the value of C5.

http://www.velleman.eu/images/tmp/DiagramMK186.jpg

The schematic doesn't list a value for C5 but you change it by replacing it with another capacitor of a larger or smaller value. The portion of the circuit that includes C5 is an integrator and first order active low-pass filter (see schematic above). It's cutoff frequency is defined by the formula
$f_c=\frac1{2\pi R_6C_5}$

Solving for C5 we get
$C_5=\frac1{2\pi R_6f_c}$

If we assume a cutoff frequency of 250Hz, C5 needs to be 6.4nF (nearest E6 value is 6.8nF). If we assume a cutoff frequency of 500Hz, C5 needs to be 3.2nF (nearest E6 value is 3.3nF). 4.7nF lies between these values and is an E3 value so it's even easier to source and it would put the cutoff frequency at 339Hz.

I recommend going with 24V LED strips if you can find ones you like. It reduces the current through the controller and/or doubles the power available over 12V. Here's one source and there are more on ebay. Don't use RGB LEDs with this controller.

http://www.superbrightleds.com/

While you're shopping, look for a housing for the circuit board since it doesn't come with one and don't forget a 12V or 24V DC power supply with enough wattage for your LEDs.

The MK/VM186 uses an electret microphone cartridge for it's input so you can't wire it to a line output without modification.

Last edited: Sep 12, 2012

Oct 2, 2009
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