Seeking Help to Create a Circuit for Arduino Nano Project

Projects General Guidance
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Hey everyone,

I'm embarking on an exciting journey and I'm in need of your expertise. Imagine this: I'm a coder with a passion for innovation, and I'm determined to craft something truly remarkable for my girlfriend. Enter OpenHoop - a fusion of traditional hula hooping joy with state-of-the-art technology.

At the core of this project lies the Arduino Nano 33 BLE Sense Rev2 controller, a versatile device equipped with Bluetooth connectivity and an array of sensors. It's the mastermind behind our vision, enabling us to synchronize LED effects with movements and sounds, creating an unparalleled experience.

Of course, we can't forget about the Adafruit NeoPixel LED strips, boasting an impressive 144 LEDs per meter. These are essential for conjuring mesmerizing visual effects, from intricate patterns to captivating pixel art.

But here's where I need your help. While I excel in coding, my knowledge of electrical engineering is limited. Specifically, I'm struggling to devise a reliable power system to support those 144 LEDs. My research suggests rechargeable batteries, preferably the 14500 type, but I'm seeking guidance to ensure smooth operation.

And this is where you come in! I'm reaching out to the brilliant minds of the internet to lend a hand. Whether you're an experienced engineer or simply enjoy tinkering with circuits, your input could be invaluable. From code review to suggestions for improvement, every bit of advice is highly valued.

If this project sparks your interest, why not give it a star on GitHub? Together, we can refine OpenHoop into something truly extraordinary and bring joy to hula hoop enthusiasts worldwide.

Here's the link to the OpenHoop project on GitHub: OpenHoop GitHub

So, who's up for joining me on this electrifying adventure? Let's collaborate, innovate, and make some magic happen!

Cheers,
Angel Camelot

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(Edited to remove the Amazon link to commercially available hoop. Found something more in line with what OP is trying to make)

In your research, did you come across this? This seems like a good way to go.
https://www.instructables.com/Individually-Addressable-LED-Hula-Hoop/

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Thanks for sharing the link! I actually stumbled upon that project before, and it's definitely an inspiration.

Quick heads up, though: I'm facing some power issues with my setup as I'm trying to power 288 LEDs for better pixel art definition. I'd really appreciate any advice or suggestions you might have to help me out with this energy dilemma.

Thanks again for your input!

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So you're designing the batteries to be charged in situ, I imagine, right? I can't imagine you'd want to take them out.
What's the longest single unit battery that will fit before it has to bend?

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So you'll want a battery, a lipo is what I'd use. Is the whole thing a 5 volt device?
If it were me, I'd start looking at Airsoft stick packs, I'll guesstimate that your highest voltage is 5 or 6 volts? If so, I'd look to a 2S (2 cell, 7.4 volt nominal, 8.4 volts fully charged) lipo with the highest mAh rating (the size of your gas tank, if you will) that will fit in the hoop design. Airsoft stick packs are pretty light and are designed for a bit of jostling and motion in Airsoft battles.
You'll have to leave a port accessible for both the plug, likely Deans (T Style red), I'd avoid Tamiya style plugs since they're a PITA to connect sometimes and longer than necessary.
Charging these requires a balance charger, it's REALLY important to charge them correctly.
Buck converters are easy to use to step down voltage without generating a lot of heat but they can be bulky so for something like this, I'd visit a local hobby grade RC shop like where they sell RC planes and stuff and pick up a Castle Creations BEC (battery eliminator circuit). These are used by RC hobbyists to ensure they don't lose power to critical electronics like steering and control surface servos and don't need a separate battery for the receiver, thus maintaining a single battery solution for their rig.
I have used the CC 10A Peak 25V BEC for years and never had one fail. I see they have a new offering at 14A peak power, the CC 2.0. I'll be having a look at one of those myself next trip to the LHS.

These things are great - pricey yes, but when it comes to power solutions, my philosophy is I'm making the best I can afford and when you buy cheap, you buy twice.
They are adjustable in software, if you have a local hobby shop, ask if they can program it for you (saves buying the Castle programmer)
https://www.castlecreations.com/en/cc-bec-2-0-010-0154-00
https://www.castlecreations.com/en/cc-bec-010-0004-00
https://www.castlecreations.com/en/pc-software-and-cables-4/castle-link-v3-usb-programming-kit-011-0119-00

Links to the new one and my old trusty, the 10A Bec, respectively. Also the programmer.
If you have a local hobby shop that sells these, I also recommend having the shop solder it up with your battery since to use the BEC, you have to solder into live battery wires and an accidental arc will really take the jam out of your doughnut, if you know what I mean. My local hobby shop offers programming BECs for free and soldering may cost only a few bucks, again well worth it if you're not experienced with soldering or don't have the tools.

Batteries: I just remembered so adding that Traxxas makes a NiMh stick pack at 12mAh, non lipo in other words, bigger and not as good as the lipos but easier to maintain and possibly safer. You'd want the ones for their 1/16 scale line of RC cars, if you can still find them. Traxxas has their own proprietary connector which is good if a bit wide, you need a compatible charger.
https://www.amazon.ca/Traxxas-2925-NiMH-1200mAh-Stick/dp/B0026R9FS8
As for the Airsoft lipos:
https://www.amazon.ca/Airsoft-Battery-Rechargeable-Capacity-Connnector/dp/B09PG5TJ85/ref=zg_bs_g_2438296011_d_sccl_6/146-0776117-9886306?th=1

Hope this gets you started.

Edit to the edits: upon further look at Holmes Hobbies, who sells this kind of thing, the CC 2.0 goes 14A peak, 10A continuous and you get two leads, one for the lights, one for the Arduino.
Note, it will work fine if you don't need the orange signal wire, the voltage you program will still be there.

bec
bec900Ă—900 64.7 KB

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Don't go with them, they are a bad choice. They work by turning each LED on and off with then duty cycle (ratio of on to off time) will change the perceived brightness.

However, the speed they do this is rather slow, so a moving hoop will seem to break up into a pattern of dots.

A better strip for this application is the strip they call "dot star" LEDs, although both have real part numbers that you can get from other vendors. These LEDs blink a lot faster and so are better than neoPixels for your application.

See :-

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Got it! :smile: Yeah, the idea is to have them charge right there. In fact, on my GitHub link, you can check out the circuit design that works for me. I had to add a capacitor, but essentially, it works perfectly with 4 batteries without removing them from the hoop.

The largest batteries I've used are AA or the 14500 ones, and they barely fit. With the LED strip in the tube, I even have to use lubricant to get them in! :sweat_smile:

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Wow, thank you so much for all that detailed information and those helpful links! I really appreciate your assistance and your suggestions for improving the project. I'll review everything carefully and consider all the options you've mentioned. I'm sure I'll find something that fits my needs perfectly. When you check out the diagram on my GitHub, if you like the code, could you do me a solid and give it a star? :star2: It'll help more people find the code, diagram, and everything else, and it'll be a big boost! Thanks again for your time and effort! :blush::pray:

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Thanks for your advice! I'm checking out the "dot star" LED strips and comparing them with NeoPixels for my project. Also, I'm hunting for budget-friendly options from different vendors. After all, the aim of this DIY project is to save some cash while having a blast! Your input is much appreciated! :blush:

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