hi guys i’m after product advice and technical assistance. i’m new to electronics and i have a project i want to do with neopixels, i essentialy need a circle 30cm diameter and the circle will have an A in it the size of the circle, i estimate 65 neopixels would do what i want spaced 30mm apartfor the most part a bit longer in a few sections. if it can be powered by rechargeable batteries i’d prefer that, and if i could run them as either plan white or rainbow colours at the touch of a button that would be good. thanks in advance for your help merv
Welcome to the forum!!
First of all lets calculate how much power some Neopixels (WS2812’s) will use at full brightness.
Each ‘pixel’ will use around 60mA at 100% brightness on each channel * 65 pixels = 3.9A. At full brightness they are astonishingly bright so you will probably end up using less. PS: an RGBW strip might be useful here if you are going for a white colour a lot of the time to reduce power consumption.
As for a specific power setup, that will depend on how long you want to run everything for and how (brightness, which colours, etc).
A rough system would go: Batteries → Voltage regulator and battery management → microcontroller and Neopixels.
Here’s an excellent guide on using them: The Magic of NeoPixels | Adafruit NeoPixel Überguide | Adafruit Learning System
As for programming you could go with the stock standard Arduino or one of the new microcontrollers like the Raspberry Pi Pico or ESP32 (both can use micropython and have lots of guides and support around)
Indeed they do, let us know if you want advice setting up your board specifically.
Also, as Neopixels are individually addressable (they’re a rename for a WS2812 standard), you can control all of the pixels in the strip to display different colours, or you can write scripts to create dynamic patterns in any colour combination you can think of.
Here are a couple of tutorials you may also be interested in if you’re new and getting started with them.
Thanks guys appreciate your feedback
No worries Mervyn,
Let us know if you have any further questions. All the best with the neopixel projects!
Do you know if I’m able to charge 2 batteries from the 1 microcontroller? 1 to power micro controller one to power neopixels
I might need you to elaborate a bit more. By charging do you mean recharging the batteries? If so there are a few microcontrollers that are more than capable of doing that with onboard charging circuits, however I’m not sure about doing it with two separate batteries at the same time…
Also, what was the second battery for? It is much easier to power a microcontroller and the NeoPixels with the same regulated power supply. Our Arduino WS2812b Quick Start Guide has a handy circuit diagram for how to wire it up with an Arduino! (it uses just a wall supply, but there’s no reason why a battery can’t be used instead)
Hi Owen, I would like it to run primarily on rechargeable batteries the reason I’m saying 2 is because I thought I read that you could only run a few neopixels through the power of the microcontroller and if you wanted to run a lot it was better to have a seperate power supply
You’re dead right there: NeoPixels (or any WS2812Bs) can draw a ton of current on full-blast so a separate supply is usually a good idea. If you’re looking to keep things simple, and you can keep the LEDs lit fairly low, the Adafruit PowerBoost 1000 might be up your alley for powering a short strip (as well as a board like a feather with its own battery if you want to keep them separate
Have a look at those and tell us what you think!
hi james thanks for your reply the powerboost looks the goods, could you make any suggestions on the best feather for my project? there appears to be a plethora of them and to be honest i wouldn’t know what half of the stuff does, i want to run around 65 neopixels, with at least 2 different lighting sequences that i can alternate between they are all plain white and rainbow. thanks merv
If you are after a plain white or rainbow pattern, be sure to limit your brightness, as the PowerBoost might not be up to the task.
Either way, the M0 Feather is a good all-rounder, and there are a ton of options depending on which connectivity options you were after
Keen to see this come to life!
thanks james i’ll grab the Adafruit Feather M0 Express - Designed for CircuitPython - ATSAMD21 Cortex M0, i looked at the powerboost i obviously missed the reason it might not be up to doing the job are you able to expllain what it’s limitations are please thanks merv
The Powerboost 1000 has an output current limit of 2 Amps at 5 volts. The maximum current draw of a Neopixel/WS2812 with full brightness white light is around 60mA each.
So your 65 Neopixels could draw around 3.9 Amps if they are all on full brightness simultaneously.
You would also need to double-check that the LiPo battery you are using with the Powerboost is also capable of whatever current draw you put on it.
thanks trent and james (and all that responded) apreciate the input. went on a spree and oredered $1150 worth of gear last night through core electronics, and got some stuff direct from adafruit, so i’m confident i can experiment and get it right. i took a gamble and also ordered 2 x 20,000 mah powerbanks they appeared to have 2a out on one usb port which i figured i could use for the neopixels with power turned down and 1a out on the other port which i can hope to use for the feather? i’ll keep everyone posted on my progress
Not trying to put a damper on your efforts but there are a couple of things I think you should be aware of here.
These power banks are designed to be a back up charging system for other devices like phones etc. They are not meant to be power supplies as such and could be quite “dirty” with switching artefacts etc. OK for charging and probably a LED supply but could have problems powering anything sensitive.
Check your specs The outputs may be 1A and 2.1A each but maybe not at the same time. The total might limit to 2.1A.
The 20000mAh is at the battery at 3.7V. This equates to 74000mWh which then becomes 14800mAh at 5V minus efficiencywhich if say 90% would end up being 13320mAh which would be the figure to work on in practice. I have a Cygnet power bank and it clearly states on the device the quoted 15000mAh is the BATTERY capacity (@3.7V). I believe this is universal with these devices. Of course for marketing purposes the larger figure sounds better.
Good luck with your project. I am not familiar with the Adafruit Feather devices.
thanks bob appreciate you messaging me, i figured i would have overlooked something so got the powerboost and some rechargables too just in case. it’s the powerbank from core electronics is there a chance you might cast your eye over it and provide your opinion? if i’m understang your post are you saying i might be able to power the neopixels with it and power microcontroller seperately? or if you had some advice on how i might achieve powering everything? thanks merv
The PowerBoost 1000 will easily power your Feather or other controlling device. Being a purpose built “supply” as against back up power it should be “clean” enough for the purpose. The blurb says it has a low battery indicator but does not say anything about low battery shut down so you would have to check and /or keep an eye on this. A lot of li-po batteries have built in low voltage shut down. If you have the model with a charger on board you can make up a unit and not have to remove the battery for charging.
The Power Bank I assume is the ROMOSS 20 listed on Core web site. Not a lot of detailed info here and most of what is on the Web is regarding the 20+. I am confidant that what I said above re capacity is true and at 2000mA (2A) instead if getting the expected 10 hrs you will only get about 6.5 hrs.
Be aware also that this unit may switch off if the current gets down to or below 100mA. Some of these units do and some don’t, my Cygnet does. This is because if the current gets down to this level it assumes the device under charge is almost full and shuts off to protect its own batteries. Don’t forget this power bank is basically a charger, not a power supply. You will have to experiment to see if this is the case. Connect about 100Ω resistor (50mA) across it and see if it stays on.
One other thing. DO NOT put a large capacitor across this device in an attempt to “clean up” any artefacts or noise. This will look like a short circuit at switch on and any protection circuitry may operate and prevent the device from switching on at all.
Hope this helps. Cheers Bob