Test Equipment
OSH Park

EEZ H24005 Power Supply

A fully open source programmable power supply with professional, lab-quality features and performance

$123,234 raised

of $44,000 goal

280% Funded!
Not Available
Feb 23 2017
funded on

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Electronic test & measurement (T&M) tools have an indispensable place on the workbenches of hobbyists, students, and DIY enthusiasts. These tools are also essential for educational and R&D institutions, who rely on them in their classrooms and labs. The EEZ Open project is an attempt to bridge the gap between T&M tools for hobbyists and students and the tools relied on in commercial, professional environments. It does that by combing the best of both sides.

Typically, the tools used by DIY groups, students, and hobbyists tend to be simple and inexpensive. Driven by a need to learn and experiment, they are generally built around free and open source software (FOSS) and hardware (FOSH). As they are passed around and shared, they create a community of users around them who are willing to assist with feedback on how to improve the project and how to avoid common mistakes. These tools are often of lower quality, have limited functionality, and lack proper documentation. That is also true of the software side, where support for some T&M instruments’ programming and interconnecting standards can be almost non-existent.

By contrast, commercial T&M offerings provide reliable and feature rich “turn-key” solutions, and they come equipped with software that lets users create centralized control of and communication between different T&M devices. However, commercial solutions also have two significant drawbacks: high cost and closed design that is often protected by one or more patents. The high cost of commercial T&M instruments makes them unattainable for the DIY & educational groups. This, along with the limited functionality of DIY tools, puts a damper on experimentation and creativity. Similarly, in educational environments, the expense of commercial-grade tools limits students’ ability to get hands-on experience.

Free and Open Source

The EEZ Open project seeks to solve these problems with a unique approach to building T&M tools. One of the best parts of the project is its software, both in terms of already implemented features and because of the availability of development tools that allow users to quickly model new or modify existing functionality for their own unique needs. This campaign seeks to launch the first device made explicitly for this software: the EEZ H24005, a dual-channel, programmable power supply whose feature set exceeds many commercial offerings.

Complete documentation and the open source software is available on our GitHub repositories, one for the hardware and one for the software. The EEZ H24005 power supply is now in its fifth revision, with three public releases completed. Firmware M3 (milestone 3) was completed in December, 2016, with support for a comprehensive SCPI command set and a TFT color touch-screen display. The command set is documented in a 100+ page SCPI reference guide.

The EEZ Open software suite currently consists of two tools:

Both applications run on multiple OS’s (Linux, Windows, OS X, etc.) with the Arduino IDE supported as a first target platform. We chose it because it’s also open source and cross-platform and well known within the DIY and maker communities. Modifying existing code, adding code to achieve new functionality, or simply uploading to our new firmware releases shouldn’t be a problem.

Another Bench Power Supply?

The EEZ H24005 is not just another programmable bench-top power supply. While its software, hardware, and mechanical aspects are designed to compete with any commercial offering, because it is fully free and open source, it provides a level of independence and hackability that simply doesn’t exist with proprietary, traditional tools.

The EEZ H24005 can’t be easily categorized as either a typical DIY solution or standard commercial solution for two simple reasons: it’s packed with features that cannot be found in DIY projects, yet its design (software, hardware and mechanical) is free and open source that is not-existent and by default still forbidden within professional/commercial solution. No more paying for unlocking additional firmware features, no more waiting for repairs or hunting for service manuals if someone makes a mistake and lets the “magic smoke” out.

Our design keeps these key concepts at the fore:

Full teardown of the EEZ H24005

Hardware Features & Specifications

The EEZ H24005 has a feature set similar to any other commercial, bench-top power supply. But it also has features that make it uniquely different. We’ve broken it all down below:

Unique Features

Local user interface3.2” TFT color touch-screen and encoder knob
Channel couplingSerial (up to 80 V), Parallel (up to 10 A) using built-in power relays (no external wiring is required)
Remote senseDoesn’t need external wiring thanks to built-in signal relays
Digital controlArduino Due (or compatible) 32-bit ARM MCU board
Power controlAC In-rush current limiter
Remote/external voltage programmingSurge protected, 2.5 V for full scale operation
Battery temperature monitoringOpto-isolated V/F input (for battery NTC)

The EEZ H24005 has a unique design that is highly efficient when high power output is required, but can also provide low ripple, low noise output for sensitive, low power circuits.

Its user-interface is also distinct. We believe the combination of a touch-screen display and single encoder knob provides a UI that successfully replaces the traditional “function” keys, keypads, potentiometers, encoders, switches, etc. With the EEZ Studio, the GUI displayed on the touch-screen can be easily modified to satisfy different users’ needs and tastes. We look forward to getting feedback from users as they interact with our GUI and make improvements and changes.

In addition, there are additional features that will be unlocked and included for free as the campaign reaches its various stretch goals. So far, we’ve reached the first stretch goal (encoder knob).

Standard Features

No. of channels2 (isolated)
Voltage range0 – 40 V (1 / 10 mV step)
Current range0 – 500 mA (0.1 / 1 mA step, stretch goal 3), 0 – 5 A (1 / 10 mA step)
Max. power per channel155 W (with selected AC/DC modules, otherwise up to 200 W)
TopologySerial hybrid (switching pre-regulator with "100% duty cycle" capability, linear post-regulator)
Built-in protection mechanismsRemote sense reverse polarity, MCU watchdog (heart-beat), Power good
Other channel's featuresOutput enable, Down-programmer
Cooling60 mm fan (speed controlled with channel's temperature sensors), passive heatsink on post-regulator's power MOSFET
ConnectivityUSB, Ethernet (USB port is now fully isolated and both inputs come with ESD protection thanks to stretch goal 2)
Other peripheralsBuzzer, RTC with supercap backup, EEPROM, SDcard socket
Remote/external voltage senseYes, using built-in signal relays (no external wiring is required for internal sensing)
Digital I/O1 x input (protected, 3.3 and 5 V level logic), outputs: 1 x opto-isolated, 1 x power relay (stretch goal 2)
Power controlAC power switch (rear panel), AC soft-start/stand-by (firmware controlled), MCU DC power switch (front panel)
AC power85-264 V / 47-63 Hz (manually selected), additional input protection (TVS, MOV, SAR)
DimensionsMetal enclosure: 293 mm (W) x 90 mm (H) x 272 mm (D)


The EEZ H24005 is composed of the following parts and modules:

EEZ H24005 modules: 1. Power boards, 2. AUX PS module, 3. Arduino shield

All modules can be easily mounted into a pre-drilled, customized metal enclosure as shown below. The enclosure consists of four parts, is made of 1.5 mm thick aluminum, and comes with screw-fixed rubber feet and front panel handles.

To simplify assembly, the number of cables has been minimized. Cooling is provided by 60 mm fan and two passive heatsinks that are also used to securely mount the power boards and further improve the mechanical strength of the enclosure.

Metal enclosure 3D model
Rear view of assembled EEZ H24005 with top cover removed


The EEZ H24005 firmware is an Arduino sketch that lets users perform all operations both locally and remotely. While local control via 3.2” TFT color touch-screen display allows quick on-site handling, remote control allows not just convenient access via serial/USB or Ethernet connection, but also makes it possible to automate many operations on single or multiple units in a classroom, laboratory, or so-called automated test facility.

Feature List

Development platformArduino IDE 1.6 or later
Local display GUI developmentEEZ Studio
Remote controlYes, SCPI
User profiles10, with auto-recall feature
Output values programming interfaceTouch-screen: keypad, step, slider; encoder knob (stretch goal 1)
Output modeStandard, Low-ripple (CPU controlled)
CalibrationVoltage and Current (multiple steps wizard, user password protected)
Output couplingYes (serial, parallel)
Output trackingYes (voltage, current, power, all protections and limits)
Event loggerYes (info, warnings, and error conditions)
StatisticsCPU and channel's total/current working hours
DiagnosticsSelf-testing, fan, ADC measurements, calibration, protection tripping

Local Control

The main home screen provides a consolidated overview of all programmed and measured output values, the status of various protection mechanisms, and easy access to system settings, user profiles, event views, and input power control (Stand-by mode). Currently three different views are implemented as shown below, and these can be further expanded for specific user needs.

Main page views: 1. Numeric, 2. Horizontal bar, 3. Vertical bar, 4. YT view

The most frequently set options are programming output values (voltage and current) and changing power outputs. So we offer three ways of setting outputs: one that emulates a numeric keypad, an encoder (step mode), and a potentiometer (slider mode). The pot works as a 2D slider with variable “sensitivity,” allowing changes to a selected value in larger or smaller increments.

Programming output values: 1. Keypad mode, 2. Step mode, 3. 2D slider mode

Remote Control

Thanks to SCPI support, one or multiple EEZ H24005s can be controlled remotely via a serial (over USB) or Ethernet connection.

Remote controls: 1. Serial console (USB), 2. Telnet (Ethernet), 3. 3rd party SCPI controller (Ethernet)

Protection Mechanisms

EEZ H24005 comes with multiple protection systems that have been thoroughly tested using various types of loads and taking into accounts edge cases such as powering up, shut down, run-time detection of cooling fan failure, etc.

Protection mechanisms are implemented at both the hardware and software level to guard to provide the maximum possible protection for connected loads and the power supply itself. Currently, the following protections are provided:

To see the EEZ H24005 in action, check out our Videos page.


The EEZ H24005 is available in several kits, from bare bones to complete kits. Assembling and using the power supply requires an understanding of electronic circuits and basic computer programming skills. We’ll be glad to assist anyone with the assembly process. Support can also be found in popular electronic forums where the project has already gotten a lot of attention (eevblog and the diyaudio forums ). Reaching out for help is the best way to avoid errors and frustration!

Pledge Levels

There are four pledge levels for this campaign:

Pledge levelBare PCBsEnclosure and AssembliesCore ModulesComplete Kit
Set of 4 bare PCBsYesn/an/a
Metal enclosureYesYes
Nuts, bolts, and electromechanical partsYesYes
Wire harnessYesYes
Set of 4 PCB modulesYesYes
3.2” TFT color touch-screenYes
2 x AC/DC power modulesYes
Arduino DueYes

Manufacturing Plan

We have already successfully produced limited numbers of prototype PCBs and metal enclosures. We’ve chosen a manufacturer for the enclosure and are currently investigating manufacturers for the PCBs and PCBA. We will source wire harnesses and packaging locally.

All modules will be tested in-house before shipping. However, end users will need to complete calibration locally by following the simple calibration wizard or remotely using SCPI commands.

Risks & Challenges

We have been working on the EEZ H24005 for the last two years and are confident we have eliminated most of the technical risk. We’ve done this by completing four prototypes and getting lots of feedback and help from the communities on popular electronics forums. Similarly, the firmware is mature and complete for its core based functionality implementing SCPI and touch-screen interfaces. We are now working to add more nifty features.

There’s always a possibility of unforeseen delays with PCB module assembly due to some part shortage or shipping issue. However, we have built a margin into our schedule to allow for such unforeseen delays. We will of course let our backers know if there are any problems that could affect the ship date.

Shipping & Logistics

EEZ H24005 components will be shipping from Crowd Supply’s warehouse in the United States. We can’t pre-pay VAT, so if your country collects VAT upon import, you’ll likely have to pay that and possibly deal with customs clearance. Therefore, the stated shipping cost does not include any applicable taxes. Unfortunately, this applies to everyone, including EU backers, as we are not able to support a parallel EU logistics and accounting operation.

In the Press



"until you check out [Denis]’s bench power supply build, you may not even know what you’re missing."

Ham Radio 360

"...explore how to connect micro controllers and single board computers to circuits and sensors to interface with the real world."


"In addition to modularity, programmability, openness, and DIY, reliability was one of the key features and design guidelines of the designing process."

Open Electronics

"The EEZ H24005 is fully free and open source."

Ask a Question

Produced by Envox in Zagreb, Croatia.

Sold and shipped by Crowd Supply.

Support Us!

We have a lot of ideas on how to make the power supply even better and development of similar open hardware even easier. Support us and we'll keep you updated on our progress, new features, and other projects.


Bare PCBs

Set of all four bare custom PCBs needed for to make your own EEZ H24005 from scratch. Designed with convenient SMT components (not included) for hand soldering.

$36 $8 US Shipping / $18 Worldwide

Enclosure and Assemblies

Includes a painted and pre-drilled metal enclosure, a full wire harness, all electromechanical parts (AC inlet, cooling fan, binding posts, etc.), and all nuts and bolts needed to mount and interconnect all modules inside the enclosure. Get this if already have the core modules or want to make your own.

$140 $8 US Shipping / $18 Worldwide

Core Modules

A complete set of all four fully assembled and tested modules that represent the core of the EEZ H24005: 1 x AUX power supply module, 2 x power boards, and 1 x Arduino shield (compatible with the Arduino Due).

$214 $8 US Shipping / $18 Worldwide

Complete Kit

Includes everything you need to assemble your own fully functional EEZ H24005 power supply using only a screw driver and pair of pliers: enclosure, wire harness, electromechanical parts, nuts and bolts, all four fully assembled and tested core modules, a 3.2" color touch-screen display, an Arduino Due board, and two AC/DC modules (power cable is not included).

$399 $8 US Shipping / $18 Worldwide

About the Team


Zagreb, Croatia  ·   envox.eu

Envox d.o.o. is home of the Envox Experimental Zone (EEZ), an open source initiative to bridge the gap between DIY / hobbyist / educational / low-budget and professional / commercial test and measurement solutions.

Project Manager
Martin Vladic
Senior Software Developer

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