This Vintage Palmtop Computer Has Ditched the AAA Batteries in Favor of a Stirling Engine
Pseudonymous maker "wiikid6" has modified a classic Palm palmtop computer with a novel power source: a Stirling engine, driven by heat from a burning fuel.
"I decided to do this project 'just because,'" wiikid6 explains of the unusual decision to build a Stirling engine to drive a vintage palmtop. "I plan on integrating a Pololu S7V8F3 voltage regulator so that I get a consistent voltage to power the Palm IIIxe more reliably."
The Palm IIIxe was released in February 2000 as one of the last two devices in Palm's III series — alongside the color Palm IIIc. Originally powered by two AAA batteries, the palmtop — a precursor to the smartphone, though lacking connectivity beyond a wired serial port and an infrared port at the top - features a monochrome 160x160 display, pen-based input with handwriting recognition based on a custom alphabet, and a 16MHz Motorola CPU with 8MB of RAM.
The Stirling engine, meanwhile, dates back to Robert Stirling's work in 1816 on an alternative to the steam engine. Designed to convert heat to mechanical work, Stirling engines served as a way to drive low-power household appliances for more than a hundred years — not known to include, it has to be said, palmtop computers.
The Stirling engine used in the project is powered by an alcohol burner and spins a generator, which converts the mechanical energy into electricity — enough to run the palmtop, though without a voltage regulator in place stability is an issue.
"~5:30 - total run time before complete failure," wiikid6 writes of the experiment. "~3.6v-5.1v - total amount of Volts reached depending on wick placement with a ~0.1V variance per cycle. 125-126mA - total amount of Amps reached depending on wick placement with a ~0.3mA variance per cycle."
More details are available in wiikid6's Reddit thread.