This project consists of three circuit boards with a row of 32 LEDs on each (actually 64 LEDs because they’re double sided). The circuit boards are mounted radially in the spokes of a bicycle wheel and batteries near the hub supply power to them. The LEDs are controlled by a microcontroller that measures the rotational speed of the wheel by way of a hall effect (magnetic) sensor. As the wheel rotates, the microcontroller turns the individual LEDs on and off in such a way that a static image appears to float inside the wheel.
Although the hardware and firmware are probably different, this project was inspired by Lady Ada’s Spoke POV.
- By running the front / back LED pairs in series instead of parallel, it now uses half as much power as version 1, yet the LEDs remain equally bright.
- By using the STP16C596 constant current LED driver instead of shift registers, the design is simplified, component count is reduced and it’s easier to build.
- The firmware shuts the circuit down automatically when the voltage gets too low to prevent damage to rechargeable battery packs.
- Switched to a low dropout regulator which gives more reliable operation when the batteries are almost depleted.
- Length of the board has been reduced slightly to fit most bike wheels that are 26" and larger.
- Spoke POV v3 video on YouTube
- Lady Ada’s website - An excellent site with lots of inspiring projects and useful info
- Lady Ada’s MiniPOV2 - A very easy to build POV project suitable for beginners
- Drewish’s project - A double sided MiniPOV for displaying text in a bike wheel
- Mikey Sklar - His "Tiny POV" project plus some interesting wearable electronics
- Bob Blick’s Propeller Clock - A clock that uses a spinning POV display
- Microchip - Makers of PIC microcontrollers
- Kits R Us - They sell a decent PIC programmer kit
- Digikey - Huge selection of components, fast delivery
- Techniks - Makers of Press-n-Peel Blue PCB film