Home I-V Curve Tester

Why now

During the July 17-19 Hacker News observation window, this technical note on making V-I curves at home received 64 points, 10 comments, and ranked 16th. This was only one concentrated discussion, but it surfaced the home-experiment moment where real curves are hard to capture and the manual workflow is fragmented.

People learning electronics at home, screening loose components, or checking solar-cell degradation would open it just after wiring a breadboard to confirm polarity and the conduction region. They would also use historical curves after swapping a component, changing a circuit, or retesting later to judge whether a change comes from the component, temperature, or wiring.

Start with two-terminal components such as diodes, LEDs, and small solar cells: limited-voltage sweeps, live I-V plots, polarity guidance, overcurrent shutdown, and two-curve overlays. The acquisition box sends timestamped voltage, current, and temperature data over USB serial; supported browsers can read from and write to serial devices directly through the Web Serial API. ^S3

Open-source the acquisition-box firmware and communication protocol, along with several reproducible experiment datasets. Publish measured-curve pages for components of the same model on GitHub, electronics maker forums, and component-review articles. Keep a hardware list and importable data with every public record, encouraging people who already have an Arduino, breadboard, and bench supply to reproduce and share tests.

Digilent Analog Discovery + WaveForms Curve TracerGoogle

It already measures diodes and transistors, exports data, and saves a current trace as a reference curve. The opportunity is not to redraw the plot, but to organize temperature, component photos, wiring diagnostics, and repeated measurements into a home-lab record. ^S2

Keithley SourceMeter / I-V TracerGoogle

SMUs can source and measure voltage and current simultaneously and are the standard professional approach to I-V characterization. A home product can only trade laboratory-grade capability for simpler wiring and record-keeping within low-voltage, limited-accuracy, clearly protected operating ranges; it cannot claim to replace laboratory instruments. ^S4

Multimeter + Bench Power Supply + SCPI ScriptsGoogle

Bench multimeters, laboratory power supplies, and SCPI scripts can produce real curves, but setup, instrument control, temperature-drift handling, and data organization are fragmented. The opportunity is to bring those steps into fixed hardware and a repeatable test workflow. ^S1

Sell a low-voltage acquisition box with a calibration component and connection protection as a one-time purchase. Basic web plotting and local storage are free; cross-device sync, batch comparison, and report export are available by annual subscription.

The hard part is not drawing sample points as a line, but making the excitation range, current limiting, calibration, contact resistance, and temperature conditions reliable enough to trust. Without clear confidence bounds, a low-cost box’s fault warnings can easily mistake poor probe contact, ADC noise, or self-heating drift for component failure. Its measurement range also limits the devices and operating regions it can cover, so the boundary between an educational demonstration and a measurement instrument must be explicit. ^S1