This DIY Calculator Has a CRT Screen and Plays Space Invaders
Oskar built a calculator with a flat CRT screen and a walnut finish that plays Space Invaders and Bad Apple. But can it play Doom?
Engineers typically take great pains to make electronic devices as small as they can. Every possible millimeter is shaved off, every trace of wasted space eliminated. Circuit boards are designed with sub-millimeter precision, components are packed tightly together, and enclosures are sculpted to hug the internal hardware as closely as possible. It is these sorts of tricks that give us ultra-thin phones that disappear into our pockets.
But are smaller devices always better? An engineer named Oskar doesn’t think so, and after seeing his latest DIY device, you won’t think so either. Oskar has designed one of the coolest calculators ever to exist — and that’s not only because it plays Space Invaders.
This calculator doesn’t have the typical character LCD or OLED display. Instead, it is equipped with a CRT screen. Oskar wasn’t worried about the calculator being a bit bulky, but he didn’t want it to be immobile, either. So rather than a typical CRT TV, he selected a self-scanning flat CRT screen. It is very similar to what was used in the Sony Watchman portable TV that was introduced in the 1980s.
The hardware design is rounded out with an ESP32 microcontroller, a 12V boost converter (for the CRT), a charging module, and a keypad. An older ESP32 chip was specifically selected because it has a built-in DAC that was very helpful for generating a composite video signal.
As for the case, Oskar used a laser cutter to slice 3mm panels of plywood. This plywood was given a walnut veneer as a finishing touch.
The calculator’s firmware is fairly basic at this time. It can evaluate compound math expressions, but it is not capable of generating graphs. But what it lacks in this area, it makes up for in extras. It can use its beautiful CRT display to play Space Invaders and Snake, which is way better than math anyway. Don’t worry, it can also play Bad Apple. That really only leaves one unanswered question: Can it play Doom?
If you’d like to try this calculator out for yourself, you can find the design files and firmware in Oskar’s GitHub repository.