Lab instruments used to be sealed boxes you either bought at full price or did without. That is changing fast. Open source projects keep bolting modern control onto gear that already sits on the bench, and the newest one targets the single most common box in any electronics lab. PSU-EXT, from MaxEELabs, gives a plain manual bench power supply programmable control without anyone cracking its case open.
What the build actually does
PSU-EXT sits inline between the supply and the circuit under test, wired through standard 4 mm banana plugs on both ends. It measures output voltage and current continuously, switches the load through an onboard relay, and serves the whole picture to a browser dashboard with live plots, history charts, protection limits, timers and triggers. Rated range is 0 to 25 V at up to 2.5 A, which covers the cheap variable supplies most ECE labs and thesis groups already own.
The parts doing the work
An ESP32-S3-N16R8 module handles processing and networking. Sensing runs through an INA240A2 current-sense amplifier feeding an ADS1115 ADC, so if you breadboard a test rig around this, your SDA and SCL pull-ups matter as much as the shunt does. The measurement side is isolated from the control side by an ISO1540 digital isolator plus an isolated DC-DC converter, which keeps your laptop off the power path when something on the test bench lets go. The sharpest trick is SCPI over USB CDC and raw TCP on port 5025, the same command language commercial instruments speak, so lab automation scripts talk to it with no custom protocol to write.
What to try next
The practical payoff is watching current instead of guessing at it. Point the dashboard at an ESP32 board during boot and you can see the Wi-Fi radio spike, the flash write, and the drop into deep sleep as separate features on a chart rather than a blur on a three-digit panel meter. PCB design, enclosure, firmware, Gerbers, schematics, the Spring Boot backend and the React frontend are all published, and pricing has not been announced yet. Read the full write-up at Hackster.io, then try the cheap version first: an INA219 breakout on your existing supply rails, logging to serial, before you commit to isolated sensing.
Originally published on blog.circuit.rocks.
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