MaxEELabs · Bench Instrumentation
Upgrade the PSU Already on Your Bench
PSU-EXT is an inline hardware module and software stack that adds remote control, protection features, live telemetry, and interactive dashboards to a conventional bench power supply — no replacement instrument required.
Working EVT-stage prototype — watch it in action- Measures
- 0–25 V / 0–2.5 A
- Control
- SCPI over USB & TCP
- Footprint
- 100 × 50 mm
Why PSU-EXT?
A programmable PSU solves remote control by replacing the instrument you already own. PSU-EXT takes a different path: it adds the same capabilities to the PSU already on your bench.
| Aspect | A Programmable PSU | PSU-EXT |
|---|---|---|
| Your existing PSU | Replaced with a new instrument | Kept — extended in place |
| Openness | Closed firmware, fixed feature set | Open hardware, firmware, and software |
| Network control | Often USB-only, or LAN-only | SCPI over both USB and Wi-Fi |
| Automation | Whatever the vendor's own software supports | Built-in scripting IDE and reusable dashboard widgets |
| Instrument scope | Locked to that one instrument | Widgets adapt to other SCPI-capable gear too |
Applications
Connect the supply to PSU-EXT, connect the load or device under test to the output, and control or monitor the session from the browser interface.
Hardware & Firmware Developers
Show voltage, current, and power trends while a device boots, joins a network, writes flash, or enters sleep. Verify real power budgets and catch current spikes a front-panel meter would miss.
Repair Engineers
Use PSU-EXT as a controlled inline gate between the PSU and the device under test. Set over-voltage and over-current behavior, then switch the output on from the browser.
Battery Testing
Sit PSU-EXT between a battery and the load. Watch voltage, current, and power during discharge, and compare runtime across firmware modes as the battery voltage falls.
Makers & Hobbyists
Make voltage, current, and power visible in a browser dashboard for demos, livestreams, or project videos — without pointing a camera at a bench PSU display.
01 — Hardware
The Board
An inline unit that sits between the PSU and the load, with galvanic isolation between the control side and the measurement/output domain, plus firmware that owns acquisition, protection, and SCPI command handling on-device.
Board
- Operating range: 0-25 V and 0-2.5 A
- Standard 3/4 in (19.05 mm) spacing for 4 mm banana receptacles
- Relay-controlled output path for enable/disable
- Isolated measurement and control architecture (ISO1540 + RFM-0505S)
- ESP32-S3-N16R8 pre-certified MCU/wireless module
- INA240A2 current-sense amp + ADS1115 ADC front-end
- USB-C for control-side power/data, with data and power-path protection
- Two external trigger inputs
Onboard Firmware
- ESP-IDF firmware for ESP32-S3 with SCPI over USB CDC and raw TCP
- Two-point voltage and current calibration support
- 100 sample/second circular buffers for voltage, current, and power history
- Relay output control, OVP/OCP behavior, timer queues, and trigger actions
02 — Software
Software for Measurements
A browser dashboard for watching and controlling a session live — voltage, current, and power widgets, protection state, and a built-in SCPI console, all backed by a browser-safe proxy to the device.
- Browser-based operator interface for control, telemetry, and configuration
- Live voltage, current, and power widgets with local-history charts
- Protection widgets for OVP/OCP thresholds and state
- Built-in SCPI console with device selection and tagged logs
- Backend proxy for browser-safe access to USB CDC and TCP SCPI devices
03 — Automation
Scripting IDE
Automate with JavaScript from a built-in browser IDE. Write a measurement or control sequence, hit run, and a dedicated PC-side task runner executes it against real SCPI devices — with live progress, logging, and time-series recording, not just fire-and-forget commands.
- Built-in browser IDE — write, run, and debug scripts without leaving the dashboard
- Sandboxed execution — scripts get no filesystem, network, or host access
- Query and control any configured SCPI device with query(), write(), and queryBinary()
- Live progress, logs, and time-series measurements stream straight back into the IDE
- Save, tag, and reuse scripts from a built-in script library
- Built-in calibration and accuracy-measurement scripts, validated against reference instruments
const voltage = query("PSU1", "MEAS:VOLT?");
const current = query("PSU1", "MEAS:CURR?");
record(new Date(), "voltage", "V", voltage);
record(new Date(), "current", "A", current);
log("INFO", "Measured " + voltage + " V, " + current + " A");
progress(1.0);
return { voltage, current };Open Source
PSU-EXT is intended to be open across the hardware, firmware, backend, and frontend. The goal is to make the core materials available in the project GitHub organization by the time the Crowd Supply campaign launches.
Hardware
KiCad schematics, PCB layout, and housing
Firmware
ESP-IDF application running on the ESP32-S3
Software
Backend proxy and the React operator dashboard
Common
Shared definitions and resources used across the project
Keep the PSU You Already Own — Add the Rest
Get notified the moment the PSU-EXT campaign goes live on Crowd Supply.
Get Notified on Crowd Supply