Re: Arduino Lightsaber

Hi guys, I've been looking at this amazing arduino topic for the last 2 months and just finished recently my first arduino-based lightsaber ! However i'm facing a powering problem. Indeed, I'm using to 18650 cell wired up in series giving me a 8V output (i know that it can drop as low as 4.5V). The output of the batteries are directly wired to the vin pin of the arduino, but also to a DC-DC StepDown module. This module lower the voltage to 5.0V in order to power my 100leds WS2812B strip at 150 for brightness. My problem is that when I use a simple external power supply for the blade only (and powering the arduino via usb), everything works fine (even tho i had to change the code mutiple time for the arduino to support a 100leds, i don't know why). However when powering everything on the battery like I explained, the blade doesn't power (voltage is still measured between the strip) but the arduino still works (for sound, motion-detection....).

If the someone could tell me what's wrong, the help would be much appreciated !

I can provide code or schematics for more details.

theguyunknown:
However i'm facing a powering problem. Indeed, I'm using to 18650 cell wired up in series giving me a 8V output (i know that it can drop as low as 4.5V). The output of the batteries are directly wired to the vin pin of the arduino, but also to a DC-DC StepDown module. This module lower the voltage to 5.0V in order to power my 100leds WS2812B strip at 150 for brightness.

My guess is you aren't able to get enough current from the converter. This is not a recommended setup. You should just use a single cell. The optimal voltage for the pixels is around 4v and 5v will just make it hotter and degrade the pixels faster.

I can provide code or schematics for more details.

Please.
It would make helping you a LOT easier than guessing.
General guidance and
How to use this forum
Especially item #7 on posting code.

How to post an image

Thank you.

There's two minutes of my life I can never recover.

@theguyunknown, do not cross-post.

jbkuma:
My guess is you aren't able to get enough current from the converter. This is not a recommended setup. You should just use a single cell. The optimal voltage for the pixels is around 4v and 5v will just make it hotter and degrade the pixels faster.

just as JB said, it would be best to run the entire thing from your batteries (parallel) at 4V. i have another project i have been working on that has a strip of 208 LEDs and am powering the strip straight from the power source (right now a USB power converter/ wall charger) but also have tested it with my Li-Ion battery pack, staight to the LED strip and the Arduino.

I built my first pixel saber over 4 years ago, and I am one of the primary contributors to LightsaberOS/FX-SaberOS, I've built a number of props for stage and video using ws2812 type LEDs.

I've got a project with 1800 pixels, things start getting way more complicated (and annoying) at that level!

  1. what step down are you using(i get it puts down to 5v but what is the amps?)
    2.why not use the step down to power the Arduino and the LED's

i am also busy building a light saber and found a lot of useful info.
also post you schematic

There is no good reason to use the step down and big 7.4v battery. It's a waste of space and energy. Your pixels need somewhere between 3 to 10 ampa depending on the color mix. The buck regulator almost certainty can't handle that if it fits inside a lightsaber.

jbkuma:
There is no good reason to use the step down and big 7.4v battery. It's a waste of space and energy. Your pixels need somewhere between 3 to 10 ampa depending on the color mix. The buck regulator almost certainty can't handle that if it fits inside a lightsaber.

Would you rather recommend a step up to 5v with one 18650 battery. Also what amps would you recommend