Signal dimmed LED's without passing current back to the signal source

  1. Hello!

    I am a bassist in a rock band and I hace slight issue with trying to rig up this

    LED Controller to do its color changing awesomeness while pulsating with what is coming out of an output on my amp (which is a "hot" and ground wire). Is there a way I can send this signal through to the LED's without running current through back to my amp? My LED strip ends look something like this:
    B G R +
    | | | |
    Last edited by a moderator: Jul 18, 2014
  2. jcsd
  3. NascentOxygen

    Staff: Mentor

    Hi TPH. Welcome to Physics Forums. :smile:

    What do you mean by "to the LED's without running current through back to my amp"? And can you explain why you'd prefer not to have to do this?
  4. The signal I'll be using to make LED's pulse is coming from a pre-amp out on the back of the amp. I don't want any power from the LED controller to go back in to the preamp. circuitry
  5. NascentOxygen

    Staff: Mentor

    The way electronics works is that what comes out of one box must return to that box. It won't come out if it can't get back. Usually the return path is through a wire called "ground" that connects all boxes, so it's a common ground. So I'd expect you'll need 4 connecting wires, R, Y, B, and ground.

    If everything is working properly, no more current will return to the preamp than left it. That should not be a problem, especially when that is how it has been designed.
  6. I looked over the instruction manual, and I don't see any way to externally modulate the LEDs.
  7. This device is designed to fit in a computer chassis and receive power from the computer's power supply at 5V DC. It then generates patterns to make the LEDs pulse which you can alter with the knobs on the device, there is no way to provide a signal to alter the pulsing, and you cannot power the device from an amplifier's output.

    For what you want you need to search for "sound to light led controller" or similar.
  8. I have a computer PSU hooked up to the controller to give it power using the bridge pin trick. The cable coming out of the controller looks like what I described in the original post.
  9. NascentOxygen

    Staff: Mentor

    I haven't looked at the manual (I'm restricted to a basic tablet here), but from what others report, I think that cable is probably output from the controller that can be used to operate more LEDs, and is not for input. It sounds like the controller makes up its own LED pattern, and is not designed to accept audio input. So it can't do what you would wish it could, alas.
  10. What if I place the signal and ground in between the controller and the ground on the LED strip?
  11. Baluncore

    Baluncore 3,305
    Science Advisor

    Please DO NOT do that, it will almost certainly not work. It will probably destroy something.

    There are ways to use audio signals to modulate LEDs, but they are not that simple.

    You should Google;
    LED Musicolour
    LED Musicolor
  12. OK thanks guys, I accidentally shorted out fried my blue and green channels shorting it out with a multimeter anyway. I'll look into that or maybe a raspberry PI.
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