Adafruit has a long tutorial on their Neopixels. Take a look at the section on power. They suggest a cap and an external power supply because each pixel will pull as much as 60mA at maximum brightness.
Adafruit has a long tutorial on their Neopixels. Take a look at the section on power. They suggest a cap and an external power supply because each pixel will pull as much as 60mA at maximum brightness.