39C3 RGB Catear Build Instructions

C3CAT with a cat ear headband around the 'A'

How much details do you need? Hold my hand please >~< I soldered before :3 Short

This guide aims to explain in simple terms how to assemble the c3cat catear build kit. If you did not get a hold of one of those kits, take a look at our BOM.

Inside this guide, you will find the following content

The general project assembly looks like this where each of the components must be connected via soldering points.

A picture of an assembled set of LED catears

┌─────┐                          ╭───╮
│ ESP ├┄┄╼ ╾┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄│   │
└─────┘
         ╱ ╲         ╱ ╲          ╱ ╲
     pluggable      long         catear
     connector      cable        & leds

In addition to one of our kits, you will need

soldering equipment
a heatgun
striping pliers
catears

Kit Content §

Out kits contain the following content:

A 3D printed case for the microcontroller, here shown in bright green
An ESP microcontroller
An RGB LED strip, shown at the very bottom of the picture
One pluggable connector with three separate wires connected to each end separated into two pieces and shown at the top of the pictures
One 10cm long, clear piece of heatshrink
One 10cm long, small, black piece of heatshrink
One 10cm long, large, black piece of heatshrink
One long cable

Flash the microcontroller §

We recommend to use WLED as a firmware on all our catears. It offers a wide range of features for display and animation and can be controlled comfortably from your smartphone.

Take the microcontroller out of its packaging and connect it to your computer via a USB-C. It will appear on your computer as a serial device.
Depending on your choice of linux distribution, you may need to ensure that you have appropriate permissions to interact with the serial device. Check your distros documentation if you are unsure or things are not working as expected.
Go to WLED-Install and follow the instructions there.
If your browser supports the Web Serial API (i.e. is Chromium based), you can flash the microcontroller directly from it by pressing the Install button.
After flashing, you will be prompted to choose a WiFi connection. You can skip this step in which case the controller will open its own hotspot to connect to later.
Flash WLED using the web installer.

Solder cables to LED strip §

One of the most important steps is to electircally connect the microcontroller to the LED strip. We will start with the LED side.

Basically, the LED strip has three connections. One for data, one for ground and one for voltage. Each of these three functions requires a separately soldered connection.

Make sure to solder to the input side of the LED strip.

A picture of the backside of an LED strip exposed. The ou label is visible on the part of it not connected to another strip segment. — The wrong side of the LED strip demontrated by the ou (out) label being on the outside.

A picture of the backside of an LED strip exposed. The in label is visible on the part of it not connected to another strip segment. — The correct side of the LED strip demontrated by the in label being on the outside.

Prepare the long cable for soldering by removing its insulation.
Strip about 1cm of insulation from one end of the long cable using your striping pliers.
The three cores inside should be stripped with something softer and finer. Your fingernails are excellent for this purpose.
Expose the contacts of the LED strip.
Peel back the protective paper from the in end of the LED strip. Also peel back the glue covering the protectors but only from the contacts, not from the whole strip segments.
Solder the three cable cores to their corresponding connectors on the LED strip. We use these combinations:

Red
+5V

Yellow
Data

Black
Ground
Put a 2cm piece of the large black heatshrink over the soldered connection.
You need to cut the 2cm piece off the included heatshrink yourself. To apply it, place it over the soldering point so that all bits of connective material are covered but so that you hide as few LEDs as you can manage. In that position, use your heat gun to fix everything into place.

Solder Cable to pluggable connector §

The other side of the long cable now needs to be connected to the pluggable connector.

Remove the insulation from the unsoldered end of the long cable and grab the male end of the plugs (the one with the pins).
Put the remainder of the large black heatshrink on the long cable. Also put one equally long piece of the small black heatshrink on each of the pluggable connectors cables. Do this without applying heat.
The small heatshrinks need to be put in place now because they cannot be applied after soldering.
Solder all the cable cores together in pairs and apply the prepared heatshrink afterwards.. We use these combinations:

Red
Red

Black
Black

Yellow
White
Apply the prepared heatshrinks. Make sure that you wrap each cable core in heatshrink individually and then put an additional heatshrink over the whole connection as a whole.

Solder Pluggable Connector to Microcontroller §

Now you need to solder the other (female) part of the pluggable connector to your microcontroller.

The front side of the included microcontroller

The backside of the included microcontroller

Solder the female side of the pluggable connector to the microcontroller.

Red
5V

Black
Ground

White
GPIO 2

Finalize the Assembly §

Place the microcontroller in the included case.
Cut off two 1cm long pieces of the clear heatshrink and put them on long cable of the LED strip without heating.
Attach the LED strip onto your favourite pair of catears. The end of the LED strip should align with the outer corner of one of the ears. After you have aligned the first part, glue the remaining strip firmly onto the ears.
The strip contains its own glue strip on the bottom. To use it, peel off the protective cover (without also removing the glue coating) and start attaching it to your catears.
To secure the LED strip, pull the two 1cm pieces of clear heatshrink over the ends and apply them there. Additionally, use the larger part of the clear heatshrink to secure the long cable to one of the ear holders.
Be careful to not apply too much heat. Otherwise, the plastic of the catears themselves might start to melt.

Congratulations! You now have a freely customizable pair of RGB catears :3

Don't feel pressured to wear cat ears – you're perfectly fine without them.
And remember: Trans rights are human rights.