This project is a $100, open-source reimplementation of Carl Michal’s Earth’s Field NMR spectrometer — reimagined for modern microcontrollers and experimental hacking. Built with general-purpose components, coaxial cables, layered PCBs, and aluminum shielding, it’s capable of executing real spin echo and nutation experiments, performing like a low-field quantum device. The original design was based on an Arduino and various specialized modules; I rewrote the entire codebase from scratch to run on a Raspberry Pi Pico, making it significantly easier to program, faster to operate, and more flexible. With DMA, interrupts, and optimized buffers, the Pico now acts as pulse programmer, frequency synthesizer, and digitizer all in one.

The project’s foundation lies in Carl Michal’s 2010 paper on Earth’s Field NMR — a technique that forgoes superconducting magnets and billion-dollar cryostats in favor of the planet’s own magnetic field. While this results in a dramatic loss of chemical shift resolution, it opens the door to truly accessible NMR experimentation. Inspired by that work, I’ve adapted and simplified the architecture for modern makers, achieving signal-to-noise ratios remarkably close to theoretical limits. Through careful PCB layout, tight analog design, and aluminum shielding, I’ve pushed the noise floor to near Johnson limits — the signal shows up where it should, and the noise stays where it belongs.

To ensure the signals are real (and not just wishful thinking or relay-induced artifacts), I implemented three experimental controls: one comparing runs with and without an initialization pulse, another involving a magnet placed near the sample to destroy coherence, and a third in which the water sample is removed entirely. If a signal survives all three — it’s likely real. Oh, and yes, you can technically play DOOM on it (on a phone taped to the top, for legal and moral reasons).

This project is for students, hobbyists, and researchers who want to explore quantum-adjacent hardware without corporate labs or dilution fridges. Whether you're here to learn spin physics, do real measurements, or just see how far $100 and a soldering iron can go.

Here is a link to the paper

https://iopscience.iop.org/article/10.1088/0957-0233/21/10/105902