Music Reactive Crown

Ideas and Tips
#1

I want to build a music reactive crown for an upcoming music festival. I have been reading up on this for a bit and needed some help to make sure my design is not missing anything. Also, if someone had a good enclosure they can recommend for the pixelblaze and sensor board that would be awesome.

Basic idea is for 144 LEDs to be wrapped in a spiral around my head. The 3 pin LED connector will run down the back of my neck and into the Pixelblaze enclosure and battery pack that are strapped to my waist with Velcro. Because of the power requirements of 144 LEDs I will power the strip using a second USB cord.

Here is my part list:
Pixelblaze board
Sensor board
pluggable 4 pin headers
solderless 3-wire connector clips
WS2812B 144 LEDs waterproof - 1 meter
24,000 mAh 5v battery bank with 2 USB ports
Cotton diffuser material
Velcro straps for crown, enclosure, and battery bank.
USB to 2 Pin 8mm Solderless Quick Connectors
3 pin LED wire connector

So what do you think? Am I missing anything?

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#2

Sounds like a fun project! Here’s a 3D printable case for Pixelblaze:

https://www.prusaprinters.org/prints/7322/related

Designed by @BanhammersWrath! Supports the sensor board too.

If you end up with a circle, there’s an included pixel mapper example for a ring that could come in handy.

I can’t really think of anything you are missing. Maybe a power switch, or do you plan on unplugging the USB to turn it off?

For one costume, I put the sensor board in my sleeve, running wires back to Pixelblaze. This let me have a few controls where it was easy to reach (potentiometers on the ADC inputs), plus the accelerometer could detect arm movements. The sensor board needs only 3 wires to work: 3.3v, GND, and a data line.

1 Like
#3

Thank you for taking the time to help me with this. I really appreciate it. When I build it, ill post it on here and Reddit and give Pixelblaze the credit.

I think the hardest thing is going to be the power supply. I’m afraid I won’t get enough Amps from a single power bank. I’m thinking about getting two 10,000+ mAh batteries at 2A each and powering both ends of the LED strip. It will make it a bit more complex to be sure. This may not even be enough for a 4 hour run time.

thanks for the suggestion on the switch. I found a USB on/off switch cord that will work. I was just going to pull out the USB cord to power off, but that is likely barbaric.

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#4

Unless you run white on an RGB (which uses 3x the current), full brightness rainbow would be about 2.9A (144 * 0.02A), and most patterns have some variation in brightness for even more savings. If you turn brightness down a little, say 2/3rd (use the max setting if you have it), you can keep it under 2A and won’t notice much brightness loss.

If you do want to run white, I recommend an RGBW strip (like the ones in my store) as a real white LED not only looks better, but draws 1/3rd the power of an RGB mixed white. With that select the RGBW mode without a minus, and any amount of white will shift from RGB elements to the W element. In other words, you’re back to about 0.02A per pixel again!

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#5

If you end up needing modifications for the case let me know I can either provide the freecad files or try to edit them if it is something specific (time allowing), can’t make any promises but it sounds like a cool idea, would love to see it come together!

1 Like
#6

@BanhammersWrath
Thanks! I appreciate the offer to make modifications. Fortunately I have a friend that is rather experienced and he has offered to help modify it if needed. I do have a question. How did you suspend the two chips in there to allow the USB port to be centered and maintain integrity with the cord being plugged and unplugged?

@wizard
After reading up on the SK9822 on http://www.thesmarthomehookup.com/the-complete-guide-to-selecting-individually-addressable-led-strips/ I was concerned about the power usage. I found the SK6812 3535 LEDs have reduced power draw and a white LED. I don’t want to be “that guy” and blind everyone in 50 ft radius so I want 25% brightness. I am looking to increase as much pixel resolution on my head as possible. My head being 24" around means I only get 3 lines of vertical resolution with 2 meters. I have to get down to 60 LED per meter for 3 meters if I’m lucky by using 180 total 3535 LEDs.

You also likely noticed I had all solderless connections. My goal is to be able to repair it without a soldering iron in primative conditions. That will be an additional challenge, but I don’t see another way.

#7

I have a little concern.
Are you using 144 led/m strip? Those can get really hot. Like melt things hots without something like metal on the back of the strip to dissipate the heat

#8

My head catching on fire valid concern. Would a mental band on top of fire resistant material under it like wool work? I’m still brainstorming ideas for a diffuser material over the top of it, so cotton is likely not a good option.

#9

@Blacklynx
I looked at that article, and while there may be slightly more current draw for idle (probably due to higher PWM frequencies), for a strip of 150 LEDs the SK9822 were within 1% of the lowest power consumption (ranked #2 overall).

Additionally, the SK9822/APA102 LEDs look soooooo much better at lower light levels, thanks to Pixelblaze’s HDR support. You can dim them down to 1/1000th brightness and still get good fades and color mixing.

If you do want to lower power consumption, lower brightness, and have buttery smooth fades, I definitely recommend the sk9822/apa102 LEDs.

There are SK6805, which has lower base current draw per element. Unfortunately there are so many clones that all use the same part numbers that it’s really nearly impossible to keep them separate and properly characterized, let alone research before buying + trying. It’s entirely possible that there are high and low current versions called “SK6812 3535” out there. This is one way to go, and will help if you are looking for lower power/lower brightness, but they are still limited to 8 bits of brightness control per channel and won’t go as low as a regular SK9822/APA102.

#10

@wizard
Damn, you are right. SK9822 LEDs are the the way to go. You have assisted me in making this awesome. Thanks again!

#11

thanks, hard to find SK9822 LEDs waterproof, any ideas?

#12

There are plenty on AliExpress …