EEZ Bench Box 3

by Envox

Modular, open-source test & measurement chassis

View all updates Dec 16, 2019

Power Output Coupling & Tracking. (And the Announcement of Our First Stretch Goal!)

by Denis Kotlar (a.k.a. prasimix)

The EEZ BB3 chassis comes with a backplane that distributes data and control signals. That backplane also provides four relays that support easy, firmware-level coupling of power outputs without the need for external wiring. You can select any one of four coupling modes: series, parallel, "split rail," or common ground. This feature includes a number of safety measures: power outputs are securely wired, which helps prevent loose connections and other external wiring mistakes; affected outputs are disabled before coupling is established; and firmware ensures that the coupling itself is performed safely.

When coupling in series or parallel, firmware automatically sets and displays output values in order to simplify usage. There is no need to re-calculate anything, and the measured values are easy to interpret.

Tracking functionality allows you to control two or more channels simultaneously. The output values, protections, and power output states of any channel in a group are kept in sync with changes made to any other channel in that group. This feature simplifies the controlled powering of a device that requires multiple power sources or symmetrical power when used in combination with "split rails" coupling.

The short video below demonstrates how easy it is to use EEZ BB3’s coupling and tracking options.

First Stretch Goal

A few people have commented on the somewhat non-standard position of BB3’s Ethernet and USB connectors, which are located on the front panel of the chassis. Our reason for putting them on the front is simple: to reduce the cost and complexity of the wire harness. Moving these connectors to the rear of the chassis would require two additional patch cables and a revised MCU module, as well as new front and rear panels.

To get a better sense of how much people want this change, we posted a Twitter poll, and it looks like this change is important to you. As a result, we’ve decided to make this our first stretch goal. If we reach $100,000 in crowdfunding, we will have enough to cover the cost of a new prototype and to deliver a modified enclosure with two additional patch cables.

In our next update, we will provide yet another example of how BB3 is more than just a power supply. We will also give you one more reason to care about that color touchscreen. Until then!

Cheers, Denis

About the Author

Denis Kotlar (a.k.a. prasimix)


$154,699 raised

of $85,000 goal

181% Funded! Order Below

Product Choices


Support EEZ Studio Development

EEZ Studio is a cross-platform free and open source BB3 development environment but also attractive SCPI controller that is used to access many T&M devices using SCPI commands. Its development and support cost us money and your donation will help us to keep it alive and kicking.


BB3 - Starter (Without Peripheral Modules)

A BB3 enclosure kit without bare PCBs but with fully-assembled core modules (AUX-PS, MCU STM32F7, and BP3C DIB 3-slot backplane). The Starter provides an environment for experimenters who are willing to build their own modules or who want a specific BB3 configuration (such as a six-channel BB3).


BB3 - Two Channel (Full)

A BB3 starter kit and two full-featured DCP405 single-channel (40 V, 5 A) peripheral power modules, including an AC/DC power module for each. A two-channel programmable power source with advanced features: remote sensing, remote programming, a down-programmer, and additional OVP (with crowbar).


BB3 - Four Channel (Full)

A BB3 starter kit, two full-featured DCP405 single-channel (40 V, 5 A) peripheral power modules, and one dual-channel DCM220 peripheral power module. Includes all three necessary AC/DC modules. This is the two-channel full kit, expanded to include two additional programmable power sources.


DCP405 One Channel Module (Full)

A full-featured DCP405 single-channel (40 V, 5 A) peripheral power module with remote sensing, remote programming, a down-programmer and crowbar OVP. Includes an AC/DC module.


DCM220 Two Channel Module

A DCM220 dual-channel (2 x 20 V, 4 A) peripheral power module and its AC/DC module.


Cable Set

Two pairs of high quality, silicone, color marked (black-red), 1 m connecting cables; a pair of clip-on probes; and a pair of insulated crocodile clips.


BB3 Enclosure & Bare Boards

A BB3 enclosure kit with a wire harness, nuts and bolts for the three core modules, a 4.3" TFT touchscreen display, an encoder knob, and an 80 mm fan. Includes a set of bare PCBs for building the three core modules (AUX-PS, MCU STM32F7, and BP3C DIB 3-slot backplane) as well as PCBs for building one DCM220 two-channel peripheral power module and two single-channel peripheral power modules (either the DCP405 or the DCP405B, as they can be assembled using the same PCB). Suitable for builders with the necessary skill, time, and patience.



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.

Denis Kotlar (a.k.a. prasimix)

Martin Vladic

Mouser Electronics

Component Provider

TME Electronic Components

Components & Hardware Sourcing

Jedinstvo - Kartona┼ża d.o.o.


Printing & Packaging

Drives and Motors d.o.o.


PCB & PCBA Manufacturing

See Also

Subscribe to the Crowd Supply newsletter, highlighting the latest creators and projects: