A long time ago I acquired a hat. Some time after that, still a long time ago, I added a blue LED strip to the band. Later again I replaced the silver ribbon with a black ribbon, removed the original hat band (cutting the glue off the hat), hot-glued a felt pocket to the inside to hold the battery, and cut a slit so the wires could pass through.

But single colour LEDs? Running off a 9 volt battery? Not good enough nowadays. Enamoured with potentiometers of late, I got the idea of doing a red-green-blue plus brightness mixing board. (Bonus points for not using radio, meaning it would remain functional at maker/hacker meetups where radio frequencies are often saturated.) I found myself in Makevember so I did up a quick breadboard prototype.

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But once I had that done I wanted to add extra modes, controllable by pressing the push button a number of times. The first one I added was Rainbow Cycle (I'm using the Adafruit Neopixel library rather than FastLED here).

Rainbow pattern
Photo by chebegeek

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Adafruit Mini Skinny NeoPixel Digital RGB LED Strip, 60 LED/m
Adafruit Flora
Bakelite Perfboard
10K ohm resistor
Momentary push button
Various jump leads
LiPo battery