Install Circuit

Replace the speaker/plastic earphone plate and screw it back together.

If your headphones have an easily-accessible channel running over the head, you can run your ribbon wire through it. Ours didn't so we just tucked the wire against the over-head piece and glued it in place (these Skullcandy headphones have a silicone over-head piece that necessitated a silicone-based adhesive).
Position the ring in the center of the earphone and use clear packing tape across the back and up the insides of the plastic earphone. The ring doesn't need much help to stay in place, so the tape helps just enough, and has the added bonus of insulating the back of the LED ring from the exposed contacts on the back of the earphone's speaker.

Use a pair of tweezers or pliers to gently pull a small amount of wire slack into the earphone through the hole you drilled earlier. This will allow you to easily adjust the headphones without yanking any of your solder joints.
Solder one wire to each power and ground (+ and -) lines of the pixel ring. Solder the third wire to the input of the first pixel in the ring. This is the "all alone" ring that goes in the second earphone.
Strip and tin the three wires of your ribbon cable that connects between earphones.
Trim down the spacer posts so they're all the same length. "Dry fit" the ring in the earphone to see if the posts are a good length. You want them to hold the ring away from the outer plastic, but not get in the way of closing the earphones up again.

The ring in the same earphone as the FLORA and battery may have to sit a bit closer to the outer plastic of the earphone to allow space for the additional components.
Run the ribbon wire into the other earphone and solder the power and ground wires to the + and - rings on the LED ring, as before, but solder the data wire to the output pad on the center pixel.

Following the circuit diagram, solder the ring's inner power bus to VBATT on the FLORA main board. Solder the ring's outer ground bus to any pad marked GND on FLORA.

Use tape to stick the ring in position, with FLORA sitting right on top of it. Plug in the charged tiny lipoly and flip the tiny power switch on FLORA to ON. Do all your pixels light up and change color? If so, great! If not, flip it off and check your circuit for shorts or missed connections, and double check your wiring against the circuit diagram.
Now we need a way to turn the circuit on and off from outside the earphones! Insert the leads of the tactile on/off switch through the hold you drilled in the earphone.

Make sure FLORA's power switch is set to OFF, and snip one of the battery's wires.
Soldering directly to the batteries leads can be dangerous! It's important to protect these wires from shorting to other parts of the circuit while working. DO NOT LEAVE UNATTENDED. Be sure to insulate each wire connection before moving on to the next step! Follow all safety warnings associated with using lipoly batteries in your projects.
Strip and tin the leads of the switch and the newly cut battery wire, then pair them up (one switch wire to one battery wire), twist and solder.

Use heat shrink tubing to insulate these new solder joints.
Set the FLORA's onboard switch to ON, and give your external power switch a click. Your circuit should power up, illuminating the earphones according to the Arduino code.

Tuck the wire connections in and use a little tape and/or Sugru to insulate the FLORA board from the headphone input board. If we had to do this project over, we'd swap the contents of each earphone so that the FLORA main board wasn't so crowded.
Home stretch! Re-install the speaker/earphone plate with the screws you removed earlier, and put the foam pads back on the headphones.
This guide was first published on Aug 14, 2013. It was last updated on Aug 14, 2013. This page (Install Circuit) was last updated on Sep 16, 2019.