The small PoV screen uses a CD player motor for high-speed rotation

The small PoV screen uses a CD player motor for high-speed rotation

Arduino Team — July 25, 2023

The human brain and eyes are imperfect, so your visual perception has a limited "frame rate". It's somewhere between 30 and 60 frames per second (fps). Most movies are at 24 fps, which is part of why they don't quite look like real life. Once you reach the upper limits of the human visual frame rate, you begin to perceive moving objects as solid blurs. This little rotating screen exploits this effect and uses a CD player engine to do it.

A PoV (persistence of vision) display like this relies on your perception of a low frame rate. It's just a spinning disc with two rows of 20 LEDs. But if it's spinning fast enough, it can cause those LEDs to flash at certain angles, and you'll perceive a solid point of light at each of those points. When the time is right, this can create the appearance of graphics like alphanumeric characters or simple images. In this case, it reveals the weather and time (in analog or digital style).

An Arduino Nano board controls the LEDs, while an ESP8266 ESP-01 module tells it which image to display based on time and weather data pulled from the internet via Wi-Fi®. These mount to a custom circular PCB rotated by a small CD player motor. Because this PCB rotates, it would have been difficult to run wires for power. So this takes advantage of wireless power transfer via coils on this main PCB and a secondary PCB below that exists solely for this purpose.

This is a smart design because it reduces cost and complexity. But the results are still quite impressive!