There comes a wonderful “MacGyver moment” in many hackers’ lives when we find ourselves with just the right microcosm of scrap parts to build something awesome. That’s exactly what [dragonator] did with his gifted tech box from Instructables. He’s combined RGB LEDs, a Trinket, and a hall effect sensor to add a semicircular rainbow pattern to his night ride while he rides it.
The theory behind the hack is well-known: given the time between pings from a hall-effect sensor responding to the magnet on a bike wheel, an embedded system can estimate the wheel rpm and predict the time to display a particular color on the LEDs. [dragonator] uses the known wheel speed to determine the LED pattern currently on display: either a slow breathing pulse to a half-circle rainbow that displays on the lower bike rim. He drops in the needed equations and required components to follow his trail in a well-documented instructable.
Persistence of Vision (POV) is a nice extension from blinking your first (or first hundred) LED(s). It’s just enough math to get the casual onlooker to cry “magic” and just enough embedded electronics to get those seasoned double-Es to nod their heads. If you’re new to the POV crowd, [dragonator’s] Instructable may be a great start.
[dragonator] really flexes his hardware skills with this project. His build includes a dip into the acid baths with custom double-sided PCBs, a technique that may have lots of scattered documentation, but no single go-to solution other than getting out there and getting your hands dirty to develop your own method.
We’re glad to see [dragonator] roll up his sleeves and put together a spinning piece of work that can actually leave the home lair, regardless of how comfortable it is down there. It’s a great testament to how a dab of math, electronics, and 3D printing can come together form a great hack from a small parts bin. We look forward to seeing what else our readers can cook up from their scraps.