The Hieronymus Machine

A modern, solid-state reconstruction of a curious piece of 20th-century instrumentation — rebuilt with today's components for study, education, and open experimentation.

Background

The Hieronymus Machine was patented in 1949 by Thomas Galen Hieronymus (U.S. Patent 2,482,773) and later popularized by science-fiction editor John W. Campbell in the pages of Astounding Science Fiction. The original device combined a "witness" chamber, a tuning ("rate") dial, a prism-and-probe analyzer, and a stroking touch plate. It remains a fascinating artifact in the history of fringe instrumentation.

Our modern reconstruction

Rather than reproduce the fragile vacuum-tube original, our design translates the concept into a clean, solid-state analog that any competent maker can build and study:

• Witness well — a 100 mL Pyrex chamber wound with 22 AWG magnet wire.
• Tuning / rate stage — a 10 kΩ rotary potentiometer with a 1 nF reference capacitor in place of the original prism.
• Amplification — three 2N3904 NPN transistor stages for stable, low-noise solid-state gain.
• Touch plate — a Bakelite sheet with a bifilar coil and a capacitive touch sensor for operator interaction.
• Sensor pad — a spiral pickup, mirroring the original layout.

A complete KiCad schematic and PCB layout (Enhanced_Hieronymus_Machine) accompanies the project, with a parts list sourced from standard suppliers such as DigiKey and Adafruit.