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Making A Sound Reactive LED Strip

Discussion in 'LEDs and Optoelectronics' started by JoshD, Mar 2, 2015.

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  1. JoshD

    JoshD

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    Mar 2, 2015
    Hey guys, I'm working on running a LED strip (like this http://www.trademe.co.nz/Browse/Listing.aspx?id=846848079) as a lighting effect that will pulse to the bass in my room (with a car headunit, amp and sub). I'm wondering how I'd wire it so I can say wire an input directly into the amplifiers output and into the LED's. I've done a fair bit of research but I can't find anything that will work with this. Any help would be appreciated, cheers, Josh :)
     
  2. Gryd3

    Gryd3

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    Jun 25, 2014
    Two things to consider:
    -Use the low-level signal wire for a control instead of the potential High Voltage sent to the speakers.
    -The light strip you have will not function as a VU-Meter... the entire strip will change color/light together.

    OK. now for the fun part! (kinda)
    What color(s) do you want?
    Do you only want it to react to Bass? (What about mid / treble?)
    Have you heard of a 'light organ' ? (You can modify an existing circuit to make this work depending on your color requirements.)
    In addition to using the line level signal between the head unit and amp, you could use a microphone to be able to react to any/all noise in the immediate area.
     
  3. JoshD

    JoshD

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    Mar 2, 2015
    Hey thanks for the reply, I want it to react to the bass lines only. I realise that I cannot directly put an input into the led strip but was wondering if there was a way to add some sort of transistor into the power input of them that gets it's signal from the amp, I'm not exactly that clued up when it comes to electronics but I'm willing to learn :p and no i'm not sure what a light organ is, I'll have a quick google now, cheers :)

    I just googled it, looks almost exactly what I'm looking for; although it's microphone controlled not a direct input. Do you think I could hack this up to take a direct input from an amp? http://www.amazon.com/HitLights-Act...F8&qid=1425360940&sr=8-3&keywords=light+organ
     
    Last edited: Mar 3, 2015
  4. Gryd3

    Gryd3

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    Jun 25, 2014
    You certainly could hack that up!
    Up to you though. You could also buy a couple parts and build one yourself.
    Those light organ circuits online are typically 3 colors. Bass/Mid/Trebble..
    All you need to do is remove the mic, put a line-in on it instead, and ignore probably close to half the circuit because you only need the portion that deals with the bass ;)
     

    Attached Files:

  5. JoshD

    JoshD

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    Mar 2, 2015
    How would I go about building my own? I think it'd be a bit more fun and rewarding to do :p
     
  6. Gryd3

    Gryd3

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    Jun 25, 2014
    Geez you're fast... I edited my above post with an example circuit... and crossed out the parts you don't need.
    You will need a very small number of resistors, capacitors, an opamp or two, and a transistor to do the heavy lifting for the lights.
     
  7. JoshD

    JoshD

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    Mar 2, 2015
    I've just got a tab open with this on it, I'm eager to get it working haha that's all :p okay okay that diagram is excellent, thank you heaps, although I'm not that good at deciphering them and it doesn't really make a lot of sense to me :/ haha
     
  8. Gryd3

    Gryd3

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    Jun 25, 2014
    They take some getting used to.
    You just need to familiarize yourself with the icons that are used...
    The zig-zag lines are resistors. The ─┤├─ sign is a capacitor. The Big triangles are op-amps.
    There is a special resistor on there that has an arrow pointing to the middle. That is a potentiometer. (Think volume knob). There is one last component which is in a circle on the far right, which is a transistor.

    The trickiest part is following the lines to determine what is connected where... but with a little practice becomes much easier. All of the icons on the schematic can be followed pretty much as is... a resistor only has two ends, and a potentiometer has 3... you may need to read a data sheet to determine what pins to go what part of the opamp though as they typically come in a little 'dual inline package' with 8 pins...

    Sorry if I over simplified.. what is you current experience with electronics?
     
  9. JoshD

    JoshD

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    Mar 2, 2015
    I haven't done any real projects like this, ie working with resistors and capacitors. I understand what they do but unsure how to use them in practice (with the different resistances and how much is needed where).

    In that diagram, it only outputs to a set of 4 LED's, how would I modify this to work with a LED strip?
     
  10. Gryd3

    Gryd3

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    Jun 25, 2014
    Well, if this is something you will want to try, you will need some supplies:
    -Breadboard. Not an absolute requirement, but will let you build and test your circuit without soldering anything.
    -Perfboard / Stripboard. This is a piece of copper board pre-drilled that you can use to make a finished project.
    -Soldering Iron.
    -Solder pump/bulb/sucker/wick. Regardless of the item chosen these things are meant to pull liquid solder away from parts... allowing you to remove and undo soldered connections.
    -Multi-meter.
    -Components! to build this project and others.

    As far as the modification is concerned, we would simply remove the LEDs in the schematic and their resistors and wire your striplight to it. If we intercept the ground wire from the striplights, you can still use the original striplight power supply and you can change colors at will.
     
  11. JoshD

    JoshD

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    Mar 2, 2015
  12. Gryd3

    Gryd3

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    Jun 25, 2014
    Go for it! Buying locally would be more of course... It's entry level equipment. You may find the soldering iron gets too hot, but that can be managed.
    Once the kit comes it, practice soldering on something.
    As far as components are concerned, ill try getting you a small list soon.
     
  13. JoshD

    JoshD

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    Mar 2, 2015
    I have done a little bit of soldering before but I'm pretty bad at it, although it's something I want to get a lot better at. Thanks heaps, it means a lot. Soon this dream will be a reality :p
     
  14. Gryd3

    Gryd3

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    Jun 25, 2014
    Parts list: (BOM)
    1x LM324 (Quad Op-amp)
    1x 2n3904 (Transistor. Or other suitable transistor. Must be NPN type)
    1x 1n4002 (Diode. Or pretty much any other suitable.)
    1x 20KΩ Potentiometer/trim-pot (To adjust sensitivity)

    Capacitors:
    - 2x 0.0022uF *
    - 2x 0.1uF
    - 2.2uF
    - 4.7uF
    - 22 uF *

    Resistors:
    - 680Ω
    - 1KΩ
    - 39KΩ
    - 47KΩ
    - 3x 100KΩ
    - 560KΩ
    - 1MΩ

    This is a 'bare minimum' list of parts. I would strongly suggest you get 2 or 3 of the unique components at the top of the list. You can get pretty much all of the resistors by buying an 'assorted' pack. (don't worry, if you miss one, you can fudge the numbers or joint two resistors together.) Same thing with the capacitors!
    Of course, you can always buy the components by themselves, this is your call. They are certainly cheap enough that you can buy plenty of spares!

    *Items dictate frequency control items... changing these values will change what notes trigger your lights.
     
  15. JoshD

    JoshD

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    Mar 2, 2015
    Okay thanks a ton, which resistors won't I need if I were to wire it to a led strip like the one I sent at the start so it just wires straight into the ground?
     
  16. Gryd3

    Gryd3

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    Jun 25, 2014
    Well. two things:
    Take a look at this instead of that potentiometer:
    http://www.amazon.com/Pins-500V-Tri...8&qid=1425571748&sr=1-12&keywords=20k+trimpot
    It's only for adjusting a signal, so it can be small. If you desired a 'volume' knob like adjustment for changes on the fly then stick with what you got. Otherwise this will let you tweak it, cover it up and put it away.

    I need to find you a new transistor... your LED strip will pull a lot of current compared to the one I linked earlier sorry.
     
  17. JoshD

    JoshD

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    Mar 2, 2015
    Yeah I'd prefer a proper knob :) would a tip120 work? just doing a bit of googling
     
  18. Gryd3

    Gryd3

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    Jun 25, 2014
    Should work for ya.
    The limiting factor here is the Amperage it can handle.
    If your LED strip is too long, you will need a beefier transistor. Or you can use lesser transistors and simply cut the LED strip into more than one segment. Each transistor can power it's own LED strip segment.
     
  19. JoshD

    JoshD

    12
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    Mar 2, 2015
    okay so a 2 amp transistor would work? a tip 112 would handle it fine?

    also, when buying capacitors, does it matter what voltage they operate at? like 16, 35, 50? cheers
     
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