The class instrument: NMR console, function generator / AWG & lab controller

Everyone builds the same instrument platform — a bench "Swiss-army-knife" every lab can use. In 2026 it is one class board, the same for everyone; Project 3 is the instrument you build on it — the firmware, the app and the housing — presented on a great project website. The hardware is deliberately standardised so the workshops, the design review and the class PCB (printed circuit board) order all pull in one direction; where you excel is the software: the interfaces, automation and polish that turn a circuit board into an instrument people love.

Project 3: build the instrument

Project 3 is an instrument of your own choosing, built on the class board: the firmware that uses the board's capabilities, the app that controls it, and the housing designed in Workshop 3 — presented on a great project website. What the instrument is, is up to you: an oscilloscope and generator, a data logger, a lock-in amplifier, a PID controller, an NMR console, a LINE or Telegram bot, a Python sweep, the camera unit… The firmware drivers you write follow from your instrument; the driver for the section you worked on in Workshop 2 is a natural start, not an obligation.

The project website is part of the instrument. It says what the app does and how to use it, shows what it can do with examples a user can follow, and demonstrates its capability — screenshots, measured results, videos or animations, and a great interface. One repository, one project website and one card on the project wall for the whole of Project 3.

What the box does

The headline: it runs a nuclear magnetic resonance (NMR) experiment. The board is a small NMR console. A coil you wind yourself, around a tube of water in a 2 mT field, puts the protons at 89 kHz; the board sends a short pulse into the coil, blanks its own receiver, records the free induction decay the spins send back, and the app shows the spectrum. Everything else on the board — the generator, the inputs, the switches — is what such a console needs anyway. Rule of thumb: the field sets the frequency. The same console reaches a higher field, and a far larger signal, by changing only the coil, the power amplifier and the preamplifier.

• Generates signals: a 16-bit two-channel arbitrary-waveform generator — DC levels, ramps, sines and arbitrary tables to about 50 kHz at ±10 V (AO1, AO2) — plus two hardware-timed trigger/clock outputs at 5 V TTL to tens of MHz, and the NMR transmitter: a direct-digital-synthesis generator and a power amplifier that drive a coil from about 40 kHz upwards, on the TX connector.
• Monitors signals: eight 16-bit ±10 V inputs on SMA connectors (AI1–AI8), with software-selectable ranges down to ±0.64 V for sensor work, logged and plotted. Inputs 7 and 8 take the NMR receiver's I and Q outputs by default, and their own SMA connectors when the solder links are moved.
• Switches things: a module header on the front panel — seven 5 V TTL lines (MODULE OUT 1–7, plus a reserved spare pin) with +5 V and ground, for driving opto-isolated modules — plus eight 5 V TTL outputs on screw terminals, two fast opto-isolated inputs and a firmware-switchable TRIG connector (in or out), plus an H-bridge and a high-current MOSFET switch fed from an external 7–18 V input for the NMR field coils — alarms, interlocks, sequenced actions.
• Talks to everything: native USB to Python, WiFi to a web page, your phone and messaging bots. Your phone is the front panel (a small OLED shows status); an optional camera node streams pictures into the same app — one ESP32-S3-N16R8-CAM 開發板 + OV3660 鏡頭 (Jinhua #41395) is available for anyone who wants to try a camera app.

The architecture

   ┌────  the CLASS BOARD: base (instructor) + 3 sections, A · B · C · one design, JLCPCB-assembled ×5, nothing to solder  ────┐
 AO1 AO2 ◄── ±10 V stages ◄── DAC8563 16-bit AWG ───────┐          ┌─── ADS8688 8 × 16-bit ±10 V ◄── AI1–AI8 (SMA)
 TX SMA ◄── OPA564 power amp ◄── AD9834 DDS ────────────┤          ├─── NMR receiver ◄── RX SMA ◄── your coil
 8 TTL out · 2 fast trigger out · TRIG in/out ──────────┤          │    preamp · blanking · I/Q mixer ──► ADC ch 7, 8
   [section B: generation, timing, NMR transmitter]     │          │    [section A: inputs and the NMR receiver]
                          ESP32-S3 dev board (socketed, u.FL antenna → SMA)
 USB-C 5 V + data (or 5 V jack) ──► ±12 V · 5 VA · 3V3 ─┤          ├─── module header: MODULE OUT 1–7 · 2 isolated inputs
 7–18 V external input ──► H-bridge · MOSFET ──► coils ─┤          └─── 16 SMA · OLED · LEDs · TTL terminals · Qwiic
   [base: socket, buses, power entry and coil drivers]  │               [section C: the front panel board]
                                                        └──────────── WiFi (phone/web app · WebSocket · OTA) · native USB (Python API)
                    │                                                              │
       [Python host: API, logging, plots]                    [PWA on your phone · bot alerts · optional camera node]
                    └──────────────── GitHub class repository + your project website + video ───────────────┘
      + main board 180 × 100 mm, 4 layers   + front panel 180 × 100 mm flat on its back: 16 SMA (3 × 6, two positions free), TTL terminals, module header, OLED, 3 LEDs   + 3D-printed box

MCU (microcontroller, the small computer on a chip) choice (frozen for 2026): an ESP32-S3 N16R8 dev board with the standard DevKitC-1 pinout and an external-antenna connector (Jinhua, NT$400), socketed on the class board and running the Arduino framework. WiFi unlocks the web/phone/bot directions; the u.FL antenna goes to an SMA bulkhead so WiFi works inside a closed metal or acrylic case; the dev board leaves 31 usable GPIO (general-purpose pins) and an 80 MHz SPI bus (a common wiring standard for chips to talk to the microcontroller) for the converters. The core circuit is standardised so the class order and design reviews stay manageable — your creativity goes into the firmware (the program that runs on the microcontroller), host software, interfaces and the enclosure.

One class board, made together. The board is a single KiCad (circuit-design program) project in one class repository (a shared project folder whose complete history git keeps, stored online on GitHub). The main board is 180 × 100 mm with 4 layers; a second board of the same size mounts flat on its back, parallel to it, on three 2×20 pin headers, and its outer face is the front panel — the face of the instrument, with 16 SMA connectors in a 3 × 6 grid (AO1 AO2 TRIG AUX TX FAST1 · AI1–AI4 RX FAST2 · AI5–AI8 and a spare position), the screw terminals for the eight TTL lines, the TX coil terminal, a Qwiic connector, the OLED, the three LEDs, the two isolated inputs and the module header. The back of the instrument is the main board's rear edge: USB-C, the 5 V jack, the external 7–18 V input and the coil terminals. The instructor built the complete board first — the base (dev-board socket, buses, power entry and rails, the external 7–18 V input, the H-bridge and the MOSFET switch that drive the field coils, and the expansion header) and all three sections — and the class finished it together in Workshop 2. The three sections: A — inputs and the NMR receiver is everything the board listens with, the eight ±10 V 16-bit inputs (ADS8688) and the receiver that turns what the coil hears into I and Q; B — signal generation, timing and the NMR transmitter is everything the board speaks with, the ±10 V outputs, the TTL and trigger outputs, and the synthesizer and power amplifier that drive the NMR coil; C — the front panel board is the face of the instrument, a 4-layer board of its own: the SMA field, the OLED and the LEDs, the screw terminals for the eight TTL lines, the TX coil terminal, the Qwiic connector, the two isolated inputs, and the module header with its 5 V buffer. The merged design went into the class order on Monday 28 September, 2 pm, and is manufactured five times — one assembled instrument each.

Rules: the instrument itself runs from USB-C or a 5 V supply, and the everyday case is ≤ 30 V DC. To switch something larger, the module header drives an opto-isolated module: the Jinhua 4-channel relay module (NT$150, about US$4.7) has opto-isolated inputs and needs about 5 mA per channel; the 12 V version needs its own 12 V supply for the relay coils, and a 5 V version is also sold that runs from the header's +5 V. Mains wiring is your own responsibility and must be done by someone qualified. Parts JLCPCB-stocked; dev board provided by the course. Cost: the class board is one design manufactured ×5, and the parts were chosen for learning per dollar — about NT$5k per student (≈ US$155) all-in: dev board, parts, 4-layer PCB, front-panel PCB and complete assembly by JLCPCB, so there is nothing for you to solder — the instructor adds the headers that join the two boards. Every part must earn its place, and the JLC quote is checked before the order.

Other ideas: add-on hardware for an ESP32-class development board

The class hardware is fixed — one board design, ordered once for everyone; nothing on this list is part of the course or an extension for students. It is here for inspiration only: ideas for add-on hardware that could be attached to a development board like an ESP32 to create other useful tools for the lab — after the course, or in your own work. The class board keeps a 2×10 expansion header, two Qwiic connectors and a few reserved footprints (copper patterns for parts not fitted), so such additions stay possible later. All use JLCPCB-stocked parts.

Beyond the baseline: build something great

The presentation and demonstration (26–30 October, about 15 minutes each) shows your instrument, your app and your website. The software, the firmware, the app and everything around the instrument are yours to push as far as you like — pick what would genuinely help your own lab, or simply what you would be proud to show:

Have a different idea from your own lab's needs? Great — put it in your spec. The board itself does not change.

The demonstration

26–30 October, about 15 minutes each. Show your instrument: what it is and what it is for, your app driving it, your project website and how a user would use it, your video if you made one. The order and the emphasis are yours — this is a product you made, not an exercise; the tutor helps you plan the demonstration if you ask.

Fallback: the firmware's simulation mode runs the app and every panel on the bare dev board — if the board is late or dead, you demonstrate that, no stigma.

Video: a video describing your app and your instrument is welcome, in the presentation and on your project website (for example through the Project 1 pipeline: Markdown → slides → website → YouTube); it is optional, and it plays if the live demonstration misbehaves.

Build plan (alongside the workshops)

The project runs during the workshop weeks, alongside your research — not a second job after the course. Every session ends with a commit (a saved snapshot of your changes with a one-line message) and a handover note; Claude walks you through each chapter as your tutor.

Fabrication lead time is the hard constraint: PCB fabrication, assembly and shipping to Taiwan take about 2 weeks (boards back around 16 October), so the Monday 28 September, 2 pm class-order cutoff is non-negotiable. The housings are printed and cut in-house — files in by Friday 9 October, 2 pm.

Presentation and demonstration (26–30 October 2026)

Collect the manufactured PCBs and housings around Friday 16 October; assemble your ESP32, PCB and housing; test and refine your firmware and app. Then, in the week of 26–30 October, present and demonstrate your project — about 15 minutes each, in English; using AI to prepare is encouraged.

• Demonstration — your instrument, your app and your website at work, in the order you choose; the video is the safety net.
• Presentation — what you built and why, what worked and what you learned; the software you built on top of the shared hardware is where you show what you can do.
• Your project websites — one per project, the GitHub Pages site of each public repository: Project 1 and its report, your phone app, and Project 3 — your instrument (firmware, app, housing) on one website from one repository. Make it a great website: what the app does, how to use it, what it can do, examples for the user and demonstrations of its capability — screenshots, videos or animations, and a great interface.

Every project is on the class project wall for how to add yours.

The idea archive

Earlier drafts of this course had a menu of sixteen instrument projects — flow interlocks, beam shutters, PID controllers, lock-ins and more. We standardised on one platform for practicality, but the archive is worth browsing: it is a quarry of software directions (many map straight onto this instrument's inputs, outputs and triggers) and of ideas for what you might build after the course. → Browse the project idea archive.