Need a quick and reliable way to verify the breakdown voltage of a Zener diode or compare LEDs under controlled conditions? The new Elektor Zener Diode Tester Kit, now available in the Elektor Store, is designed to make component characterization easier for electronics enthusiasts, makers, repair technicians, and engineers.

Based on an Elektor Labs project by Philippe Le Guen, the compact instrument functions as an adjustable constant-current source, allowing users to measure Zener diodes up to 54 V while also testing LEDs and other semiconductor devices. Instead of building a dedicated test circuit every time a component needs to be checked, users can simply connect the device under test, select the desired current, and measure the voltage with a multimeter.

Flexible Testing for the Electronics Bench

The tester offers six selectable current settings: 1, 2, 5, 10, 20, and 50 mA, making it possible to observe how components behave under different operating conditions. It is powered from a standard 5 V to 12 V USB-C supply, while an onboard DC-DC converter generates an internal voltage of up to 60 V for testing higher-voltage Zener diodes. A switchable 5 V output limit also helps protect unknown devices from excessive reverse voltage during testing.

The tester also features dedicated 2 mm banana sockets for test clips and 4 mm banana sockets for connecting a multimeter, making it easy to monitor the voltage across the device under test while maintaining a precisely controlled current.

Beyond measuring Zener diodes, the tester can also be used to characterize LEDs and other two-terminal semiconductor devices. The accompanying Elektor Labs project even demonstrates how the instrument can be used to compare the brightness of LEDs connected in series, highlighting its versatility for electronics development and troubleshooting.
 

Tester in Operation

Build It Yourself

The DIY kit includes the PCB, enclosure, and all required electronic components, allowing builders to assemble a practical bench instrument from scratch. The detailed construction documentation guides users through PCB assembly, enclosure preparation, wiring, testing, and final assembly.

The Elektor Zener Diode Tester Kit includes the PCB, enclosure, electronic components, connectors, and hardware needed to build the instrument.

One of the strengths of the project is its well-documented construction process. The Elektor Labs article explains each assembly stage, from soldering the PCB and mounting the power transistors to wiring the controls and verifying the selectable output currents before the enclosure is closed.


The finished tester features a compact enclosure with a rotary current selector, USB-C power input, dedicated measurement connectors, and a front-panel test button, making it both practical and easy to use on the workbench.
 
During final assembly, the PCB is wired to the front-panel controls and connectors before the enclosure is closed.

Whether you're identifying unknown Zener diodes, comparing LEDs, troubleshooting a circuit, or adding another useful instrument to your electronics bench, the Elektor Zener Diode Tester Kit offers a practical solution while providing the satisfaction of building the instrument yourself.

For more information about the Elektor Zener Diode Tester Kit, visit the Elektor Store. To explore the complete circuit design, construction guide, measurement examples, and engineering background, check out the accompanying Elektor Labs project, where you'll also find the schematic, PCB layout, and other project resources.

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