In the world of electronics, graphics can generally be categorized as either vector or raster. Vector graphics are drawn by following the path of the lines, like what you would do when you draw a simple illustration with a pen on paper. Raster graphics are created by turning on pixels one horizontal line at a time — something that doesn’t come naturally when drawing on paper, but which is easy enough for a computer to understand as a data array. Almost all monitors today display raster graphics, but YouTuber Arcade Jason has created what may be the world’s smallest vector monitor.
Modern LCD displays are well-suited to raster graphics, as the pixels are naturally arranged in a handy grid and can be addressed in tidy rows one at a time through multiplexing. But tube monitors and TVs were almost completely the opposite. They use a cathode-ray tube (CRT) to shoot an electron beam at the screen, which emits point of light — a bit like shining a laser pointer onto a wall. The beam is then moved in the X and Y axes to draw a picture. In order to produce raster graphics, which includes television broadcasts, that beam has to move in horizontal lines very quickly, one after the other, while pulsing on and off to create the entire picture. If all you want to do is create basic line drawings, it’s actually a lot easier to simply move the beam like you would a pen.
Vector CRT monitors like that have been used in a number of applications, including the unique Vectrex video game console. But to make one on a small scale, Arcade Jason used the CRT tube from an old camcorder viewfinder. That CRT’s screen is only about the size of a nickel, as it’s intended for you to hold up to your eye. It was simple enough to turn the electron beam on and off, which only required finding the proper pins on the small power board to send 12V to. Directing the beam was another story, and Jason had to create his own yokes.
In a CRT monitor, the yokes are magnetic coils that are used to deflect the electron beam in the X and Y axes. Physically moving the electron gun with motors would be far too slow and imprecise, so the yoke coils are used to deflect the beam in direct proportion to how much voltage has been applied to them. Arcade Jason used a hand-wound toroidal inductor for the job, which is just large enough to fit around the CRT. As he demonstrates, this setup is fully capable of drawing vector graphics on the tiny little screen. We can’t verify whether or not it truly is the world’s smallest vector monitor, but it’s not a far-fetched claim.