Turning an AR7778 Musical Calculator into a MIDI Instrument

When I was in school, the pinnacle of calculator technology was the Texas Instruments TI-83 — the Silver Edition if you were fancy. It…

Cameron Coward
a year agoMusic

When I was in school, the pinnacle of calculator technology was the Texas Instruments TI-83 — the Silver Edition if you were fancy. It wasn’t just that it was a requirement for high school math classes, it was also because it could be used to play games programmed in BASIC. I, for one, did more programming than math on mine. But, it turns out I was too easily satisfied, because the $10 AR7778 calculator plays notes when you push the buttons and the TI-83 didn’t. YouTuber igor30 took advantage of that to build a MIDI instrument.

Unlike the TI-83, the AR7778 isn’t even a graphing calculator. It’s just a boring old calculator like you’d get as a gift from the bank when you sign up for a new checking account. But, pushing those buttons does generate sweet synthetic notes. igor30’s build utilizes that functionality to play music. It works with an Arduino Nano, which actuates solenoids via relays to push the buttons.

The musical sequences are programmed on the Arduino Nano, and it simply toggles the solenoids as needed. Each button on the AR7778 plays a different note, so it’s just a matter of presses the buttons necessary to play a tune. igor30 has programmed a number of songs with the setup, including the MacGyver theme, the Pirates of the Caribbean theme, the Super Mario Bros. theme, and — after apparently running out of themes — Despacito.

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