Overview
The Photoelectric Effect Demonstrator is an all-in-one laboratory instrument and demonstration platform for observing and measuring the photoelectric effect with a phototube. It pairs a low-noise analog environment with a transimpedance amplifier whose range is switched digitally to capture nA photocurrents, and a variable supply that sets the stopping potential across the tube. An onboard ATSAMD21 manages the measurements, display and controls.
The analog side runs from isolated ±12 V rails, separated from the digital side by multi-channel isolation so the microcontroller doesn’t disturb the phototube signals.
The goal is a complete, self-contained tool for teaching the photoelectric effect and characterising photocathodes. Planned milestones include a 3D-printable light-tight optical enclosure, automated stopping-voltage sweeps, and data logging to a PC over USB.
- KiCad
- Low-noise analog
- ATSAMD21
Updates
-
Rethink and reboot
The design had grown well over the initial budget, so the project is getting a full reboot: revisiting the research into vacuum tube fundamentals and simplifying the circuit design to cut complexity.
-
TIA ranges, power and UI
Reworked the transimpedance amplifier’s feedback selection, the board power and the user interface.
-
Digital isolation
Reworked the digital isolation block between the analog sensing domain and the microcontroller.
-
Fresh start
A major overhaul of the project, including removing the laser from the design.
-
First circuit concept
Started the project with an initial circuit concept.
Commits
Loading commits…
View all commits on GitHub →