Sean Heber Builds an Electronic Etch A Sketch the Hard Way: With No Microcontroller
Built from discrete logic chips and 555 timers, this dot-matrix drawing toy wears its inspiration proudly.
Maker Sean Heber has built an electronic equivalent to an Etch A Sketch toy — but decided to take the long way around, creating it on breadboards from discrete logic chips without the benefit of a microcontroller.
"It's not actually a real Etch A Sketch. of course," Heber admits of his creation, "but it kind of works like one — except instead of using pulleys and belts it uses electricity and wires, and instead of gray aluminum powder my screen is made of LEDs."
The original Etch A Sketch launched in 1960, built by the Ohio Art Company and based on L'Écran Magique (The Magic Screen) designed by inventor André Cassagnes. Effectively a hand-driven XY plotter, the toy is controlled using a pair of knobs to move a stylus using a series of pulleys and belts — scraping a layer of aluminum powder from the screen, rendering parts transparent. Resetting the device after you've drawn something is as simple shaking the toy to coat the screen once more.
Heber's version drops the mechanical components and powdered aluminum in favour of electronics — controlled, like the analog original, using two knobs at either side of the display. Said display is a quartet of 8×8 single-color LED matrices, though it's not connected to a microcontroller; instead, Heber opted to use timing circuits based around the classic 555 and discrete logic chips to read the rotary encoder inputs and move a cursor around the screen — leaving a glowing drawing in its wake.
"[It works] by displaying bits from the RAM one pixel at a time, hundreds of times per second [and] our normal persistence of vision will be enough to make it look like a solid image," Heber explains of the circuit. "This project was probably way beyond my electronic skill level when I started it, but I'm really happy that I managed to pull it off anyway. All in all, it took over a month to figure out my approach and to get all the parts that I needed."
The build is documented in full in the video embedded above and on Heber's YouTube channel.