I've cut and soldered myself an 88 led string of ws2812b to use in my holiday display, but I think I'm having power draw problem that I'd like some help resolving.
Using the adafruit neopixels library, I find that initializing and lighting more than around 60 leds at once causes the Uno to reset. Thankfully there's been no smoke but I can't help but think it's a power draw issue. The neopixels Vin is fed by the uno's 5v out and I'm using USB power.
So I guess my question is, do I need a dedicated power supply (i.e. not USB from wall wart), do I need to power the less separate from the uno, is there a way to easily modify the circuit to keep everything compact?
Each pixel can take 60ma.
Power your strips with an external 5 volt power supply.
Adafruit discusses how to power your strips, they sell power supplies for this.
Do not power your strips from the Arduino.
Just as LarryD mentioned, the Arduino board has a limit to the amount of current that can be drawn from its pins depending on temperature etc but the amount of current that comes into the board thru the usb is aproximately 500mA and this is distributed in the board. The 5v pin supplies whatever current is left, each ws2812b LED can draw upto 60mA and by this limit, you will be able to power on no more than 7-10 LEDs at a time.
I would recommend getting an external power supply for lighting up a large number of lights.
Thanks. I'll start looking into that. In the meantime I found I was able to get things working by cutting the brightness of each pixel in half, which is plenty bright, with nary a reset and no noticeable heat issue on the board. Since it could be running for hours at a time, I'll keep monitoring it, but so far all is well.