Help: Sound activated 12v LED strip lights powered by battery packs on a flagpole.

Discussion in 'The Projects Forum' started by tachedout, Jun 4, 2015.

  1. tachedout

    Thread Starter New Member

    Jun 4, 2015
    Hello All,

    I'm a total newbie and I have been searching all over the internet without success. This site seemed to have the most helpful responses, so I thought i'd ask here.

    Project: Portable battery powered flagpole with sound activated 12v RGB LEDs. ( will be used for camping/festivals/night time events.)

    I'm planning to run in total 6ft of RGB LED strip lights. I don't have much info on them as they were given to me from a friend, but the markings on it says 12v and has 3 leds per section (see picture 1).

    I'm planning on using 3/4" EMT conduit and its going to be about 20ft tall. The top 2ft of the flagpole will have the LEDS (3 x 2ft strips)

    I'd like to have the lights activated by sound during festivals to flash with the beat. Everything that I've seen online seems to use a headphone jack vs a mic. If it used a mic, it was connected to a large breadboard which I don't want. I'm hoping to have something similar to what powers those LED/EL Tshirts. (hoping to be the size of this controller: I hope someone can help.

    Power supply options:
    znooda 5600mAh power bank (similar to this:


    9.6v 3000mAh Ni-MH battery packs (

    I would like the top of the flagpole to light up in this way, but just flash with music and not just stay on or light in a pattern ()

    How I would like the lights to flash:

    I was going to just buy one, but from researching this project I'd like to learn and it seems really interesting and fun. I'm hoping to try Arduino or Adafruit in the future, but would like something very basic to start. Any and all help will be greatly appreciated and please excuse my lack of knowledge as I would say I'm below newbie and have no idea where to start. =)

  2. ericgibbs

    Senior Member

    Jan 29, 2010
    An important problem when using a microphone as the sound sensor and speakers for sound output is acoustic positive feedback.

    If not designed correctly the system could 'howl'.
  3. tachedout

    Thread Starter New Member

    Jun 4, 2015
    Thanks E! I didnt' think about that and figured it would work like the tshirts. Hopefully someone has a way to get around that.
  4. Bernard

    AAC Fanatic!

    Aug 7, 2008
    Just under your tytle there is a red " Search Forums". Put in Color organ. If only just sound is desired, use just one color organ chanel. With one signal & 3 colors, colors could be alternated.
    Looks like about 36 segments where ea. seg. has 3 LEDs in series,; @ 20 mA drain = 240 mA. With battery of 5.2 Ah @ 5V, use boost convertor for 12V, now Ah = 5/12 = 2.1Ah. Minimum time 2.1 Ah / .24 A = 8.75 h X .75 efficiency = 6.5 hours operating time.
  5. korchoi


    Jun 5, 2015
    This sounds really interesting.Now,about driving the strip, i need more info on your RGB LED Strip.
    Also, some concerns(all based on approximations of the RGB strip):
    The battery will probably not last long.
    Typical LED's use a few milliamps of power. For low power, each can suck up 1mA. 5 mA should be enough.
    However 5 milliamps stack up quickly in large numbers. Given there are 5 cells each feet of strip(there's probably more),
    your rgb strip will use (6feet) x (5LED's) x (5mA) = 150mA.If all 3 colors are on, this goes up to 450mA.
    There is also the power loss from the boost converter you will have to use to increase the voltage.
    Given an optimistic 70% efficiency, 450mA will be 70% of the actual current draw.Final result: 642mA for white light strip.
    But wait, there's more! 642mA x 3 is the actual draw from the 5 volt battery if a voltage tripler followed by a 12V regulator is your DC boost choice.
    draw from 5V battery with 70% efficient voltage tripler: 1928mA;
    5V battery life with load: 5600mAh/1928mA = 2,9 Hours of LED action!

    The batteries must sustain high currents on discharge.
    The 5V battery gives only 1A of current, insufficient; The 9V one, on the other hand, will happily deliver up to a maximum of (3000x2)=6000mA=6A

    The box with the voltage booster will build up significant heat. This might damage the battery pack if on the same box.
    power draw = 15x1.928 = 28,92W

    30% of the power is dissipated in the voltage tripler and the regulator will cause about 3v drop, so they will build up heat.
    loss on the voltage tripler: 30% 28,92W = 8.676W
    loss on the 12v regulator: 1.928A x 3V = ~5.8W
    total loss: ~15W
    with the same amount of power, a soldering iron melts tin wire.The heat generated might as well hurt your skin if you make the box too small.

    did i ramble too far?
    tachedout likes this.
  6. ebeowulf17

    Active Member

    Aug 12, 2014
    I didn't see any mention of speakers or audible output; thought the op was just looking to light LEDs in response to sound, in which case feedback isn't an issue.
  7. tachedout

    Thread Starter New Member

    Jun 4, 2015
    WOW I knew someone would be able to answer my question. In response to the color organ, I did search that and none seemed to be sound activated. They were all using an mp3 player or audio connector. None were using a mic. Also none were battery operated which made it difficult.

    From reading korchoi's response, it sounds like what I want is a lot harder than I thought. The box housing the circuit would be towards the top of the flagpole and I was planning to run the wires down to the bottom to have an easy connection for the batteries. I was planning to have it at the top because I figured that would be best for the microphone so that other sounds wouldn't interfere and only the music would be driving the flashing.

    I also have white leds and I might use that as it seems the RGB light strip seems to draw too much power. Are there any recommendations on what I need to build the color organ/sound controller? (sorry not sure what is the correct name is) Right now it looks like I should start with just the plain white led's as to save on power. I'm hoping the flashing will help to conserve power and I won't have it on all the time. I also have quite a few battery packs, so I hope I can get a few good hours of use out of also helps people to find us in the dark.

    I really appreciate the responses!
  8. AnalogKid

    Distinguished Member

    Aug 1, 2013
    Most color organs are designed to use a speaker output as the controlling source. To use a microphone for the source, you will need a microphone preamp. There are many in past threads on this forum, or you can search for microphone preamp kits. Lots of them out there. Some use one opamp, and some use only 1 or 2 transistors. Finding a circuit that runs directly off the battery should not be dificult.

    What is your comfort level building a small circuit on perfboard or on a small pc board in a kit?

  9. simpson89

    New Member

    Aug 3, 2015
    hello fellow festival-lover tachedout,

    i stumbled across your flagpole project here and as it so happens i am facing the exact (but really the 100% exact) same problem of building a sound sensitive LED-flagpole here. google doesnt seem to help out very well on this matter (how to power LEDs, sound-controller and mic for a decent amount of time and without using up too much space), so i was wondering if you have made any progress on this and could share how fare you have gotten?

    thanks in advance!!!