Scientific calculators, such as the Casio fx-991MS, are extremely useful for basic arithmetic, computing trig functions, and the like, but have their limitations. These limitations, of course, help test whether or not students have learned certain material, as they don’t have the same abilities as a graphing calculator, and certainly can’t access the Internet like a phone.
While that’s true of unmodified devices, as shown in Neutrino’s video below, it’s actually possible to integrate WiFi into one of these calculators. In this hack, he subs in a tiny OLED display for the solar panel that normally handles charging, producing a spy-worthy gadget that looks nearly stock when the “extra features” are turned off.
The modified calc uses an ESP8266 module to connect to the Internet, which allows it to fetch pre-uploaded data from Google Firebase. To keep things as stealthy as possible, Neutrino came up with a clever interface comprised of embedded sensors and magnets that can be hidden in a pen cap.
Neutrino’s device is activated through a reed switch and handheld magnet, while the 'button' controls — navigating the menu, selecting items, and scoring content — are accomplished through magnetic taps and double-taps on a pair of Hall effect sensors. There’s even basic chat functionality, though options for sending messages are naturally a bit limited.
The magnetic design means there’s no extra buttons to reveal its secret, and that the actual calculator capabilities are largely left alone. Solar charging is obviously no longer available, but a LiPo is added to power the new accessories, which can be charged via wires that barely poke thought the bottom of the unit.