The earliest tv units
Lately, YouTuber bitluni has been exploring the world of show applied sciences. This has ranged from easy LED matrices to holographic persistence-of-vision spinners and even a foray into constructing a customized cathode ray tube (CRT) tv. However alongside the best way, bitluni got here throughout one of many earliest kinds of dynamic screens: the Nipkow disk, which was patented in 1884.
In precept, the disk is comprised of a single spiral that has a collection of evenly-spaced holes minimize into it, and when mixed with a motor, photodiode, and toggleable mild supply, photos might be recreated on a display screen that sits throughout one part of the disk.
Constructing a mechanical tv
Idea now in-mind, bitluni instantly set to work designing and 3D printing the primary disk, its holder, and a small display screen that would sit over a small a part of it. In lieu of some type of photosensor to detect the place/pace of the disk, bitluni as a substitute went with a NEMA17 stepper motor and A4988 driver. This helped to simplify the code and electronics considerably at the price of a decrease framerate.
With the mechanical parts assembled, the final half he wanted was the sunshine supply. Much like how a CRT makes use of an electron beam to light up a skinny layer of phosphorous and provides the phantasm of a strong picture, this mission’s ultraviolet LED mixed with a reactive plastic card permits the collection of projected dots to briefly persist onscreen earlier than fading away, thus contributing to the general image.
Transmitting video
The ultimate activity of constructing this mechanical tv set was figuring out how you can get movies from one supply to seem on the disk’s small display screen, and after some tinkering, bitluni determined to go along with an ESP32 growth package as a consequence of its small dimension, WiFi connectivity, and quick processor. It really works by repeatedly receiving new video frames from a customized net app through a websocket. Each time a brand new one has been obtained, the stepper motor goes to the recognized beginning place and rotates based on the specified framerate whereas the UV LED is concurrently pulsed to lighten or darken sure areas of the body.
On the net aspect of issues, customers are in a position to seize video from any supply due to the browser’s built-in display screen sharing API. This stream of photos is then resized to suit the disk’s dimensions earlier than being outputted to the ESP32. Bitluni experimented with screens of assorted supplies and located that the non-fluorescing ones did not expertise almost as a lot burn-in when uncovered to UV mild.
To see extra about how this mechanical TV was constructed, you may watch bitluni’s video right here on his YouTube channel.