You can go longer or shorter, more or fewer depending on the look you’re after and your budget. Strips can be different lengths if desired. Both the 30 LEDs/meter and 60 LEDs/meter strip (or a mix) can be used. The former is more affordable but more sparse…looks fine for a random “sparkle” effect, while the 60 LEDs/meter looks better for smooth motion effects along each dread. Don’t use the 144 LEDs/meter high-density strip though…that type doesn’t have the silicone sleeve, which we rely on for extra durability and “body” to the hair.
Making a full head of hair requires a lot of ribbon! Our headpiece used about 20 meters and was still too sparse — the thin spots needed to be filled out with strips of craft foam. 30 meters of ribbon would have been about right for this design.
If you have extra NeoPixel strip, you may want to make a couple spare dreads in case some don’t work, or for repair or replacement later.
For long strands and whole reels, testing is best done with an Arduino Uno or similar microcontroller; the Trinket only has enough RAM for about 100 NeoPixels.
A 5V DC supply powers the strand, with a 1000 µF capacitor to prevent surges to the pixels. Both ground and data are connected to the Arduino.
- Start a thread in the Adafruit Forums describing the problem, ideally with a photo that clearly shows your wiring and power setup…we’ll take a look and troubleshoot any common problems. If the strip is defective, we can then arrange for an exchange.
- If you’re in a serious rush and can’t wait for a replacement, and if it’s just one or two bad pixels out of the whole reel: depending how you plan to divide up the strip for this project, you might be able to cut around the bad pixels, salvaging the good segments between them.
The 2-pin JST connectors (if your strip includes them) may come in handy later. Set them aside, or add them to your parts bin for other things.
You should already have a plan at this point for how you intend to divide and distribute the LEDs around the headpiece. Ours was simple: ten equal-length segments of 15 NeoPixels each, but yours might be more complex with different lengths. Sketch it out in advance or try a mockup with a foam wig head and strips of paper.
There are electrical and software factors, too. The Trinket board only has enough RAM to manage about 100 pixels, and has a maximum of 5 output pins (our design pairs up the NeoPixel strips, each pair always shows the same pattern of lights). If you need more pixels or fully independent control of many strips, you might need to step up to an Arduino Micro or a Teensy board.
Alternative: if you’re making different-length strips, see if you can reorder the cuts to skip over these joints.
This project, more so than others, requires competent soldering skills and a quality iron in good working shape (you’ll see why shortly). An old hand-me-down iron with a crusty tip isn’t going to cut it, nor will weak “cold” solder joints.
Use stranded wire for this project! Solid-core wire does not take well to repeated bending, which wearable projects tend to see a lot of. 24 gauge is ideal, but a little thicker (22 or 20 gauge) can work too.
The color-coding will save your sanity later when hooking everything together. It gets quite “hairy!”
Most of these will be trimmed shorter later…a little wasteful, but much less frustrating than trying to plan every wire’s length (and finding you having to splice extra wire later).
As with the prior steps, it’s most efficient to do this in bulk; cut the wires for all the LED strips now.
Again, batch process your work. Strip all the wires!
See those little arrows? Those indicate the direction that data moves. You want to make sure you’re connecting to the input end of the strip, labeled “DIN”.
Tin the tip of the iron and touch it to the wire and copper pad on the strip, allowing both to heat up for a moment before adding more solder.
Properly done, solder will flow onto the pad and saturate between the wire strands. If the solder beads up on the surface, that’s a cold solder joint and will soon break.
Do not heat a blob of solder on the tip and then move it to the joint. That’s just a recipe for failure.
When briefly testing short strips like this, it’s usually okay to power them from the Arduino’s 5V pin. The initial demand for current may cause the Arduino to “brown out” and stop; if the LEDs do nothing at first, try pressing the Reset button.
For longer strips, use the same power supply and capacitor as before.
If a strip doesn’t light up, make sure you soldered to the “DIN” (input) end, and check for solder bridges or other connection problems. Set aside any problem strips. When you’re done testing the rest, go back and fix the soldering on these.
Both of these tools use a lot of current. They should be plugged into an outlet with no other major appliances on the same circuit. If there’s a coffee pot or a microwave oven on the other side of the wall, this can trip the circuit breaker if they’re all running at the same time. Run both tools for a moment to check that everything’s okay.
If there were a Rule Number One for wearable electronics, it might be “never use current-carrying wires as a load-bearing element.” Guess what we’re about to do…
Our goal is to make sure the solder connections don’t get strained and crack clean off. Yet they’re right at the base of the “hair,” where it attaches to the head. The very point of most flexing.
To accomplish this, the connections at the end of the strip need to be potted — encased in a solid material to help resist shock and vibration. This is why the solder connections must be flawless, because they will be inaccessible from this point forward, permanently encased in a blob of plastic.
The tubing used here is about 1/2 inch in diameter before heating.
Slide a piece of tubing over the strip, about an inch from the wired end.
The following photo sequence shows these tools operating less than an inch from bare fingers. Do not interpret this as “harmless.” These tools WILL bite.
The heat gun really is necessary; a lighter won’t cut it. We’re using a big tube and we’re trying to keep the glue molten at the same time.
Once cooled: the ends of the strip, the wires and the solder connections are firmly encased in a solid blob of plastic and should be impervious to just about anything.
Slide a bit of heat-shrink tube to the ready position and squirt some hot glue into the LED tube, both front and back.
Add a bead of hot glue all the way around the end of the heat-shrink tubing.
The goal is to create a sort of flange at the end that will later be used to secure this strip to another part.
If you encounter a dud — if a solder connection broke or the strip was damaged from all the heating — your options are limited. Sometimes it’s easiest just to make another, if you have extra LED strip available. Otherwise you can try sacrificing the first LED…cut off the wires and trim the first LED, then strip and re-solder the wires to the input of the next LED and re-test. If it works, seal it up and test again. It’ll be one pixel shorter than before, but most likely nobody will notice the difference.