The great thing about these NeoPixel strands is that most of the wiring is already done for you; we just need to make some connections at the ends.
We'll show making an adapter for the microcontroller, then attach the NeoPixels with their included connector. Power connects at the opposite end of the light strand. That’s something frequently overlooked with NeoPixel projects: while color data must travel in a specific direction from “in” to “out,” power can go either way. In the diagram above, a 5V power supply is connected at the end of the strand, and we tap off this at the start of the strand to power the microcontroller, where the strand’s data input is also connected.
You can easily chain multiple light strands together with their included connectors. Just remember that if you have more than a few strands chained together, you may need a beefier power supply. A modest 2 Amp supply is good for a couple strands, or more, depending on how you set the brightness level.
We've added a diode near the power supply to protect our pixels from too many volts. A lot of inexpensive power supplies aren't super accurate: they're labeled as 5v and they give off 5v-ish, and it's sometimes closer to 5.5 or 6.
These neopixel strands can be pretty finicky, and they really don't like more than 5v. Adding a diode between the power supply and the LED strand will compensate by dropping the voltage just enough, so we get around 4.5-5.7 volts.
Alternatively, you can use a switching power supply with a 3 or 4.5 volt option, or one that's rated for 4.5 volts or lower. Just be sure you don't switch the supply up to 6 or 12 volts, or you could fry your controller and pixels!