Zener Diode Meter 1V to 50V

Zener Diode Meter 1V to 50V


Zener Diode Meter 1V to 50V


Presented here is zener diode meter for testing voltage value of an unknown zener diode. The zener diode or diode voltage regulator is a special diode, Unlike normal diodes these diodes are intended to work in the breakdown voltage and an essential part of the voltage regulator circuits.

These components maintain constant voltage at its terminals suffer variations even when substantial current, its connection with reverse bias is normal also to work in the zener voltage of the source Vs must be greater than the rupture Vz, as always condition using a resistance Rs in series to limit current to a value always less than its maximum power.

Zener Diode Meter 1V to 50V


D and all who walk with electronics is known that the task of finding out the characteristics of certain components is at best boring, with the zener diodes happens that the quantity of values ​​is very large and to find their Vz we have to spend some time looking a component that most of the time is very small, needing the help of the magnifying glass and learned patience and the marks of the body of the component, if not the Vz value printed on the body we can see its features and at the end as it passes almost always not the courage it takes.

Checking the status of the zener diode is usually done with a normal multimeter scale to measure diodes, this test gives us a precise idea of the state of the component, but does not give us the value Vz the zener, the zener diode tester is truly practical when we want to find out quickly the value of the zener Vz measured.

zener tester



Mounting plate prototypes.

Supply without batteries, 230V .

Read value Digital Vz

Zener diode tester 1V to 50V

Two scales 5mA and 15mA test


As can be seen the circuit is simple, starting with a transformer with two secondary 24V are rectified and filtered to obtain a voltage of approximately 80V, followed by a voltage regulator circuit formed by (R1, R2, D1, D2 and Q1) which reduces the voltage to about 52V to avoid spending the maximum voltage limit LM317AHV integrated controller.

The LM317AHV is a high voltage version LM317T can reach a maximum of 57V. The 37V LM317T can only reach a maximum at this point where we can not confuse the component otherwise it may not last long circuit.

The setup is mounted on LM317AHV constant current generator has been added to a switch circuit (S2) in series with resistor (R4) to choose two test scales (5mA and 15mA) as power zener diode to be tested.

As usual in practical circuit design and all that really can be easily assembled with standard components, and if it can be recovered from all types of devices to reduce as far as possible the cost and environmental degradation.

The recovery of electronic components is not difficult but it is a bit laborious, but nevertheless is quite rewarding and the way we learn many things from the apparatus for which they try to recover the components.


I have changed the voltage from 12V to 9V to power the panel meter with a small supply 0.2 A adapter-switched and it really is very easy, only needs to modify the value of the voltage divider circuit TL431 pre regulator.

resistance to replace is the one directly connected output + terminal and the source of the TL431 RFE I have put 100K LIN because the resistance to calculate the new value out 9V rare and in this way is only fair and ready.

Zener Diode Meter 1V to 50V

Zener Diode Meter 1V to 50V

Zener Diode Meter 1V to 50V

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