An open-source electrochemical impedance spectroscopy (EIS) and frequency-response analysis instrument, built from the ground up toward professional-quality, low-cost, sovereign lab instrumentation.
Experimental. Active, early-stage R&D. Expect churn and rebuilds. Work is tracked here at edgecollective while it develops; a curated multi-repo ecosystem comes later, once the R&D settles.
zZtop grows an impedance-measurement instrument in small, cross-validated steps. The digital measurement engine runs on an Electrosmith Daisy Seed (STM32H750) under Zephyr: coherent DMA waveform generation feeding a streaming software lock-in, producing swept Nyquist spectra on test networks.
The analog side starts with a minimal two-probe front-end, whose job is to keep the output impedance of the Daisy Seed's PCM3060 audio codec, and the coupling capacitors on its outputs, out of the measurement. It goes back to basics: the classic adder potentiostat (Bard and Faulkner, Electrochemical Methods, Ch. 15), which pairs a potential-control amplifier, a reference voltage-follower, and a current-follower transimpedance stage.
That design picks up the lineage of our earlier olm-pstat (presented at Open Hardware Summit 2013, with a schematic contribution from Jack Summers) and the later four-probe work, simplified to two electrodes first, before we earn the four-probe version.
firmware/ Zephyr applications and the out-of-tree board definition
host/ Python tooling that drives the instrument and analyses its output
hardware/ circuit designs and simulations
docs/ project documentation
data/ captured measurement data
See CONTRIBUTING.md for conventions.
Circuits are defined in code with tscircuit, so the schematic, the netlist and the simulation come from one source and the design history is the git log. KiCad and ngspice handle rigorous capture and validation.
First-stage prototypes use through-hole DIP parts, which keeps the research phase quick and reworkable. Later development moves to modern surface-mount parts.
Each area builds on its own. For the circuit designs:
cd hardware/two-probe-frontend
npm install
npx tsci build # compile, validate, run the simulation
npx tsci dev # interactive schematic and PCB preview
Firmware build instructions arrive with the board support.
Open source; license to be finalized. Hardware and software will be released openly.
Development on this repository is assisted by Anthropic's Claude Code agentic platform, under Craig Versek's direction and review.