Connect with us

Help needed: 16 LED sound reactive setup not bright enough!

Discussion in 'LEDs and Optoelectronics' started by martinlink, Dec 8, 2012.

Scroll to continue with content
  1. martinlink


    Dec 8, 2012

    Just finished a project with 16 LEDs (8 green, 8 blue) wired in parallel groups of 4 x 4 in series, attached to a TiP31c transistor and to the PC's 12v line from a Molex. The audio signal comes from the onboard HD audio header on the motherboard (Asus P5QL Pro).

    The setup works ideally then in Always-on mode (wired a 3-position switch with always on, off and sound-reactive mode). The lights are ultra bright and the illumination is awesome.

    The problem: when in sound activated mode, the LEDs only emit a faint flicker, if anything. The 4 LEDs closest to the power source are just a hint brighter than the others, but about 20% of the maximum brightness in always-on mode.
    Also I noticed that if I crank up the volume in VLC player to 200%, the lights actually get dimmer and start to just flicker sporadically.

    The LEDs are 3v, 20mA (

    So any suggestions on what to try to turn this thing into a real light show? (preferably without any major changes as it is already secured into the PC case...)

  2. KJ6EAD


    Aug 13, 2011
    Reduce the base resistance if you have any. A schematic of your circuit would be helpful, if you have one, not the one you found on the internet, one that accurately represents your circuit as built.

    You probably need an amplifier but that would be more building.
  3. martinlink


    Dec 8, 2012
    Hey, thanks for the reply

    Here's a sketch I made prior to building the setup. I know it's not the best but it was just for guidance so I wouldn't get lost while building it ;)

    I'd not like to get an amp as this was meant to be a cheap weekend project. Also, there is no resistance to the LED-s, they run on 3v, so no resistor needed...

    Attached Files:

Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day