As mentioned in the site’s inaugural post, I previously pursued electronics as a hobby. Back in 2009, I started NBitWonder, a DIY electronics website and blog, with a close friend. It ran for a few years until being shut down in 2012. Over the course of its life, it enjoyed some success, including mentions on a number of popular electronics websites such as Hackaday, Make, Adafruit, and Dangerous Prototypes. I worked on several projects in that time, and the first one I ever published was CardPOV.
Persistence of Vision (POV) is a technique in which LEDs are blinked through various combinations in a pattern. By timing these blinks to coordinate with when the LED moves through a particular place in space, a ghosted after-image can be used to form words, pictures, videos, and more! Persistence of Vision was a reasonably mature technology in 2009; still, in the arena of open source offerings the main contenders were the DIY kit-oriented MiniPOV v3 from Adafruit Industries and application-specific POV devices, such as those offered by Monkeylectric. I wanted something small, something pocketable, something business-cardy.
Thus, CardPOV was born! The design was quite simple, and it blinked through a simple set of hard-coded 7-bit binary numbers, lighting up the device. A CR2032 coin cell and holder were installed on the device, allowing for power from a (relatively) slim profile. I created a limited run of 8 of the devices, and gave them to family members as stocking stuffers for Christmas. A demo of the project can be seen below:
Challenges of CardPOV
The main challenge of the CardPOV project was the lack of a fixed mechanical platform to produce repeatable motion of the POV display. Without a fixed platform, the CardPOV image is blurry and the human eye tended to have a difficult time tracking the text put out by the device. Most successful POV devices make use of fixed mechanical mounting to ensure a repeatable path of motion.
Status of CardPOV
At the time of this writing, CardPOV is not seeing active development, with the latest available version being 1.0; development focus is presently situated on higher priority targets. CardPOV does have room to grow, however, and may become the subject of development at some point in the future. In the meantime, CardPOV is open source hardware, and relevant project files are available on github.