Introduction: Sound Reactive Neopixel Bangalore Torpedo

Picture of Sound Reactive Neopixel Bangalore Torpedo

So we had another snowfall in NYC and I got the idea that things would look pretty cool lit up with LEDs.

How about creating a light stick to jab into the snow so that the snow itself would diffuse the light. Even better if you can have flashing lights or have it react to sound and music. Making this lets you explore the way light is diffused through different media and play with colors.

This was a quick experiment to try but works better under nighttime apres ski or club conditions.

(I'll reshoot a video sample at night with the strandtest running just to show off the lights)

Oh, if you didn't know, bangalore torpedoes are long tubes of explosives that are connected together to form a longer device to clear paths through battlefields. This light borrows the same form factor but explodes with bursts of colorful light. Go Engineers!

Step 1: Field Expedient Improvised Electronic Devices...

Picture of Field Expedient Improvised Electronic Devices...

So I had the remnants from my Star Wars Neopixel Crossguard Lightsaber laying around. Sure, I could have pieced that back together for a regular lightsaber but surely there was something else to transform it into.

It contained an Adafruit Neopixel strip of 60 Neopixels. It was controlled by an Adafruit ATtiny85 based Trinket

Step 2: A Little Trinket...

Picture of A Little Trinket...

You can go on Adafruit's Learning System to follow the tutorial for the Trinket Sound Reactive LED Color Organ.

This uses Adafruit's microphone module to trigger the lights. The Trinket translates the loudness of the sound into ranges of color displayed with the Neopixels.

We just need to modify the code a bit to take account of more Neopixels used and comment out the potentiometer variable since we want full brightness. There needs to be some adjustment for the noise level present in the electronics and circuitry.

I reused the same breakout board I had made for my Star Trek Enterprise Turbolift light. When connected to USB power instead of batteries, the lights are a bit brighter. This would work well with a lithium polymer battery pack.

The circuitry and battery pack can be fitted inside the tube but I left it outside so it would be easier to reprogram and change the batteries. Tape up and seal the ends to keep moisture out.

Step 3: May the Flora Be With You...

Picture of May the Flora Be With You...

The Trinket LED Color Organ code was derived from sound reactive projects using a different microcontroller such as the Adafruit Flora which is more a full Arduino. Since the ATtiny85 chip is smaller, the response is also different so I had to really experiment with adjusting the noise level filter variable in the code. The light level should really fall back or start at lights off. In the video you can see I only got it to move a bit with it's constant high range.

A better implementation of the LED sound reactive color organ can be found on the original Adafruit Ampli-Tie project or used in the following instructables made with the Flora:

Neopixel Ring Shower Massager Light

Neopixel Ring Headphone Mod

Go ahead and make a few sound reactive light sticks to place in the snow or even waterproof them and toss in the pool or water. Stick them in the ground for a seismic monitor. Put up a whole array of them in a public space as interactive art. Maybe just hang them up for a cool wind chime light that reacts to the urban or rural soundscape. Spread the light.

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