New to Arduino and forums so any info is amazing. Basic question and double checking so I dont damage neopixels and/or board. If I hook up higher than 5 volts, lets say 6 volts/9 volts to the VIN or DC in, respectively, will it down the voltage to 5 volts over the digital pins for output? i.e. powering neopixel strip. I know I can only use about 8 neopixels or so before I have to hook up external power of 5 volts source to power more pixels. The project Im working on will have roughly 150 pixels I want to stay away from the wall wart because the project I'm working on will need to be mobile and run off AA batteries or equivalent. That's also another aspect I'm reading up on but any info is awesome! thanks in advance!
All can be answered here:
.
You need at least 7.5V if you are using the Vin pin or the barrel jack (assuming you are using an Uno, you did not say). Yes, you can get away with 8 neopixels when running on usb power. Maybe 10~15 with 7.5V 1A external psu. But those estimates are cautious. They assume all leds might be full brightness white at the same time. In practice, if the neopixels are showing other colours, are flashing of are at reduced brightness, they will draw far less current than the maximum and you can use a longer string.
For 150 leds, get an external 5V psu. That many neopixels could draw 9A.
For battery projects, avoid using regulators, either external or on-board the Arduino. Use a dc-dc converter, they are far more efficient. Avoid usb battery packs, they are often also inefficient.
"For 150 leds, get an external 5V psu. That many neopixels could draw 9A."
Make sure you connect it's ground to the Arduino Gnd for a common reference point.
If I hook up higher than 5 volts, lets say 6 volts/9 volts to the VIN or DC in, respectively, will it down the voltage to 5 volts over the digital pins for output
No. You feed Neopixels with more than 5V and it burns up.
You have to supply it with 5V although it will work at about 3.5V.
Do not forget to use a resistor in the data line and a large capacitor on the supply.