Maker Tom Farnell, who says he “construct[s] issues that in all probability should not exist,” has put collectively a pocket calculator with a greater-than-10-year battery life because of the continued decay of radioactive tritium — although with a giant caveat about how lengthy you should utilize it every day.
“Nuclear-powered units have been utilized in area exploration for many years, offering auxiliary energy in areas the place solar energy alone is inadequate. Radioisotope thermoelectric turbines, akin to these powering the Voyager probes, convert warmth from decayed plutonium into electrical energy utilizing thermocouples,” Farnell explains. “Since acquiring plutonium will not be possible, we’ll make use of tritium, a hydrogen isotope, which slowly decays and emits beta radiation.”
Tritium, also referred to as hydrogen-3, is a uncommon radioactive isotope of hydrogen. Because it decays, with a half-life of round 12 years, it provides off a visual glow — resulting in its use in every little thing from luminescent watch faces to gun sights to novelty keychains. It is this glow which Farnell harnessed to energy the pocket calculator — by way of the pleasingly easy however nonetheless efficient strategy of strapping a number of tritium vials to a photo voltaic panel.
“By using low-light photo voltaic panels manufactured from amorphous silicon,” Farnell says of the know-how, which incorporates tinfoil shielding and a capacitor to retailer the generated vitality, “we are able to convert the emitted gentle into electrical energy. This know-how, generally known as radiophotovoltaic batteries, affords a captivating different for long-lasting energy.”
The tritium vials are sandwiched between two photovoltaic cells, to transform their gentle into electrical energy. (📷: Tom Farnell)
That could be true, however whereas the challenge was technically profitable it comes with a significant caveat: it takes a full night time of charging to get one minute of utilization out of the calculator. “Regardless of the restricted energy output of the tritium tubes,” Farnell admits, “our tritium-powered mini calculator efficiently operated for roughly one minute after charging in a single day , which is a promising end result contemplating the minimal vitality generated.”
Nonetheless, the calculator’s radiophotovoltaic battery does, as promised, supply a shelf-life of greater than a decade — with extra particulars accessible in Farnell’s write-up on Hackaday.io.