Build the BandBlinker - 120v Audio Trigger on the Cheap.





Introduction: Build the BandBlinker - 120v Audio Trigger on the Cheap.

To help compliment the BandBlinder, a cheap but good working stage light kit for a friend's band, I've also created the BandBlinker, an audio trigger for the light kit made with inexpensive, easy to find parts.

Step 1: Gather Materials

The materials for this audio trigger should be pretty easy to source. Radio Shack, a hardware store, and an auto parts store should have everything you need between them. The materials you need are as follows:

1x sound triggered car effects light with adjustment dial
1x shallow "new work" wall gang box
1x three prong wall outlet
1x wall outlet cover plate
1x 12v relay (the higher the amperage it can handle the better off you'll be)
1x project box (to hold control circuit)
1x computer power cord (the thicker its wire the better)
1x 12v AC adapter
large wire
super glue

Tools required:
soldering iron
knife/ dremel (to work cases and open the light)
wire strippers

Step 2: Deciphering the Light Controller

To get the trigger you need for the later steps, you must first figure out where you're triggering line on the effects light is. First use the knife or dremel to remove the back of the case which holds the circuit board for the light. *BE CAREFUL* the light itself is powered by a high voltage transformer that steps up the 12v the light is fed to what is probably a few thousand volts.

That being said, hook the light's power wires to the lines coming from the 12v AC adapter, making sure you can make the light function as it's meant to, usually with a normally on, and variable sensetivity audio triggered mode.

Now get your multimeter, set the light to a sensetivity that you can trigger it with your voice, and probe for a spot on the board (probably somewhere near the middle) that is at 12v when the light is on, and 0v when the light's off. these two points are what you will attach the coil of the relay to later on. You may want to mark them for later reference. Different brands of lights will likely have different boards, but the concept of how they work should be similar enough for our purposes.

Step 3: Much Bashing and Breaking

Now it's time to have a little destructive fun. disconnect the AC adapter from the wall, and excise the board that lives inside it. We want the board out of it's "wall wart" case so that it can be more easily fit into our project box later on. I've done this many times, and the easiest way i know is to cut the wire off as close to the case of the AC adapter as you can, push the rest of the rubber stress relief into the case, then use needle nose plyers to tear chunks of plastic off until you're able to get the board out. Try to work along the seam of the case. Be careful to not hit or otherwise damage things inside the wall wart as the temptation to hit it with a hammer becomes intoxicating depending on how well the adapter you're gutting is glued together.

Alternatively, you could also just add a barrel plug to your project box and use the adapter as is, but it's not as slick if you have to use two outlets to power this box now is it?

Now that you have the power source for your light's board laid bare, you'll want to do the same for the control board in your light as well. pull the board out of it's case, keeping about 6" of the the 12v power cord on, but cutting or desoldering the lines that feed the tube of the light itself. these are those high voltage ones we talked about earlier, and you want to make those as small a target for finger touching as possible.

Step 4: Connect the Bits and Bobs

Now that you have all your materials thoughrougly torn to bits, it's time to put them together how we want them. Below is a block diagram of how my trigger box is wired. Feel free to ask me any questions in the comments section about it. Basically the AC adapter powers the control board, which triggers the relay when sound is loud enough, activating the relay and the power to the outlet. The lines between your relay and control board are the ones you metered out and marked in the previous steps.

Step 5: Testing and Assembly

Now would be a good time to test the whole circuit with a desk lamp to make sure it works as it should.

Once you're happy with how it works, you can start putting it in the casing. For mine, I melted a hole in the case for the adjustment dial to stick out of, made a hole for the power cable to sit in (knot the power cable so it won't come out), and made a notch for the wires feeding the outlet to exit the project box from. I then mounted the outlet in the gang box, added it's cover plate, and super glued the gang box to the project box so that if I need to I can take the screws of the box off and get to the insides again. I also glued the boards and relays into the project box so they don't go anywhere.

Step 6: Completion and Usage

Once everything is complete, you can test the whole thing again, adjusting the dial to the volume you want it to go off at. You can hear the clicking of the relay inside, which makes for a neat sound and feel if you hold the box as it's doing it's thing. Putting the whole control box near the source of audio you'd like is a good idea, but if the amp is too loud, moving it away or putting it in something that insulates sound might be a good idea (though you'll want to make sure you don't have it overheating or shorting out since sound insulators are usually good heat insulators as well.)

Other than that, You just need to hook the BandBlinker up to your BandBlinder or even a desk lamp or other light and rock away. Hope you found this instructable helpful.



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    What type of relay is needed? Can this be one from an auto parts store like: How about using a fuse and/or a GCF outlet for this project? Also, does the mAh matter for the power supply?

    I'm wondering about using this for a single "rope light" or in other words strand of led's wrapped in plastic which use 120V/60Hz.

    I've looked into plenty of different solutions such as "Color organs/light organs" or rope light controllers.

    The above which I've stated seems to be un-necessary and or un-needed for what I'm attempting to do considering it would be a single flashing light following the beat.

    What I'm wondering exactly is if I would be able to remove the 'mic' which you've implemented in your design and some how directly feed a line from my surround sound receivers bass output into the device causing it to trigger the rope light to be powered every time the bass speaker has voltage sent to it.

    Any help, suggestions, comments, or even ideas, would be greatly appreciated I'm wanting to do this for a party I'm having on Halloween so an answer as soon as you can as well as possible what kinda time line this project requires would also be appreciated.

    2 replies

    Also it might help to mention that I have no previous experience in electric engineering.

    Nor light setups...

    Most I've done is a bit of very very crude and un-professional wire cutting and re-wiring back in the day and wrapped electrical tape around it to keep it together after twisting the wires together rather then properly soldering them and adding an enclosure for the custom adapter.

    So this would be one of my first official projects in the area/field,
    I do however know of an electronic store that would have mostly all the parts and any they don't... I'm sure radioshack would have what they don't.

     This might be a bit of a big task to take out as a first time project. I'd suggest you read up on how electronics work for a bit, practice soldering on an old radio or vcr you don't care about to get a feel for how it works. Get your wire tips coated in solder before you try to solder them to a board. A basic 30 watt soldering iron and the roll of normal flux-core solder from radio shack should be fine to work with. I'd read a couple of instructables on soldering too so you get an idea of how it's best to do it.

    For the light controller, making one just like mine should be fine for the rope light. You could try putting a 1/4" jack in place of the mic and run that to your amp, but it might be too sensitive that way. You could also install the jack, then make a 1/4" cable with a plug on one side and the original mic on the other end so you can move it around to the best place to get it to trigger as much as you need it to.

    Hi there, I saw your BandBlinker project, great! I would like to ask if you could give me advice on the following : I am designing a light installation, simulating a graphic VU meter for the Art's Complex studios building in Edinburgh, Scotland (see attachment). When I saw your tutorial I thought maybe you know if it would be possible to make two series of 31 100 Watt bulbs work with this setup? even if I d have to break it up into sets of 3 lamps it would be great. I hope I m not taking to much of your time. Many thanks , Mettje

    2 replies

    3100 watts of draw means you'll be pulling down about 14 amps at 220v, so make sure you have around a 20 amp breaker dedicated to each of those lines. You should be able to use the exact same control circuit as I set up as long as your relay is able to handle the current draw on the switched side. A car (or maybe a lawn mower) solenoid should do the trick.

    Thanks so much for your reply, I am a complete novice in this field, but I ve looked up what you wrote, and managed to understand it, brilliant!

    i figured it probably had something to do with the alternating current not channeling through the direct current of the broke-down adapter. will have to try again this afternoon...thanks.

    which set connects to the closed side of the relay, and which side connects to the switchable side of the relay? i assumed the negative from the AC Power connects to the switchable side and the control circuit from the effect light connects to the closed side. also, when testing the relay made a constant buzzing while the light stayed on, is that normal? the problem i see with that is the clicking sound from the relay triggers on the effect light cuz it was so noisy...thought?

    1 reply

    you may have had the AC on the solenoid pins of the relay rather than the "switch" side, which would have made the solenoid open and close at 60 or 50hz. Try swapping where the two pairs of wires to the relay go.

    Actually, unless you have an EQ pedal around, it'd probably be better to just get a second hand light kit.

    so i really like your setup, im trying to figure out a simple setup like this, but where its on a controlled dimmer for the BASS, TREBLE, VOCALS how do i get the dimmers to those specs?

    1 reply

    I'm not sure exactly how you'd go about that. You might be able to replace the mic on the trigger circuit with a 1/4" jack and feed a mic with an EQ pedal into it, but I don't know if the levels between the mic and circuit would be the same.

    could any one give me a more in depth procedure for step 4? its very vague.

    2 replies

    What in particular are you having trouble with?

    Oh, sorry for the late response I managed to figure it out. Thanks for the cool Instructable!

    Nice Instructable! If you can't find that exact light I believe they sell items that do exactly this; (maybe at a party store)

    just wondering where i can get one of those lights from? i cant seem to find one.

    1 reply