Hardware Making: LED cat ears

LED cat ears – I’m a netcat!

I’ve been having a couple of loose ideas buzzing around my head about what I can do with 10 meters of single addressable LED’s that I ordered from Ali Express. Slowly they have been incorporated in different projects, and the latest one: a pair of cat ears!

LED cat ears — because one can never have to many LED’s!

You’ll need:

  • A headband
  • tons of hot glue
  • cardboard
  • fabric
  • a microcontroller (i.e Digispark)
  • LED’s (WS2812B or Neopixel)
  • soldering iron, solder, wire cutter, wire stripper
  • some cable – I used the cable to an old Christmas light
  • a resistor
  • A USB cable and a computer, and a workshop to be in, and ideally a solder fan so you don’t breathe lead and flux all night
  • A computer with Arduino IDE and Digistump board manager and driver.

First thing first: I need a headband that fits my giant head without getting me a headache. The one I got I found at Drogeriemarkt in Germany for about 2 euros.

Then I cut out cat ear shapes from cardboard, googling a shape that I wanted. I didn’t get it right the first time, I just redo it until it’s done. I cut and bent them so that they followed the shape of the headband.
Next step: hot snot (or as it’s also sometimes called: hot glue). Lots and lots of hot glue. Hot glue doesn’t like to stick to smooth plastic like the headband, but just using a lot helped.
For this project I slaughtered a pair of ear muffs that I found on second hand. I was surprised to see the amount of fabric I actually had to use — and again, there is a lot of hot glue used. The fabric added a lot to the structural integrity of the ears.

So now that I had a pair of ears I could measure how many LED’s I needed. I could have gone for 8×2 or 10×2, and I thought the more the better. I took the LED strip out of its silicone tubing and just bend it at the middle. WS2812B LED strips are easily bendable and thus excellent for pointy ears. And yes, there are 6, not 10 pixels in the picture.

In the pic there’s only six pixels, while I used 10 for each ear

With the help of some upcycled black Christmas light cable,a 330 ohm resistor and some shrink tube I soldered the first 10 LED’s to a Digispark microcontroller. The LED’s I use are WS2812B, which is the same as the brand Neopixel.

The most tedious part of this project was to get the Arduino IDE and the Digistump Board to work on my Windows machine. I was missing a driver that will (as far as I remember) be plug’n’play on Mac. As soon as I figured that out, everything worked the charm. I’m not a fan of fiddling with the Arduino Programming Language, so I uploaded a nice little sketch courtesy of Adafruit.

Painting the microcontroller black and gluing it to the back of the ear

Now that I verified function of the strip, I measured the distance between my cat ears, cut up some more upcycled black cable and soldered the second LED strip in place. Gluing the strips to the ears, I started at the tip of the ears working my way down. I also glued the cable in place. The microcontroller I painted black with nail polish and secured it to the the base of the back of one of the ears, with a little bit of adhesive foam plastic.

The finished LED cat ears

A you see, hot glue is all over the place.The project is currently powered using powerbank over USB. Here are the schematics. Happy soldering!

The schematics of the cat ears – super simple!

Below I am wearing the cat ears together with choker/headband that has the same basic design. I’ve been teaching this very circuit to the attendees of the conference adaconf which I am a co-founder of. Most of the time I wear the battery pack to my wearables in my sports bra. In this case the choker’s battery is in the bra whereas the ear’s battery is fastened with hairbands in my updo! It’s a question of what you’re aiming for I guess. Since I like cyborg estetique I think that visible cords and batteries is quite nice, but should I feel like it I could solder a LiPo battery and LiPo charger in place as well.

LED cat ears and LED choker at adaconf1