How to test electronic diode using a multimeter

To test an electronic diode with a multimeter can be a big task if you’re not familiar with electrical components. However, it’s a vital aspect of practical electronics as it aids in troubleshooting electrical faults.

Therefore, in this guide, I’ll walk you through the steps to test both digital and analog electronic diode using a multimeter.

An electronic diode is a two-terminal electronic component that allows the flow of current or electrons in only one direction. It is a very important component of which most of our electronic devices can not do without.

How to measure the value of a resistor using a multi meter.

As an electrical engineer or technician is not enough knowing only the working principle of the diode. But also, knowing how to test diodes and determine weather is faulty or good. More especially, when building a project or troubleshooting electronic devices.

This blog will educate and give you guidelines in testing a diode using a digital/analog multimeter.

Testing a PN diode using an analog multimeter

The following points should take into consideration when testing a PN diode.

• Plug in the probes to a multimeter to their ports, (black to com and red to V-ohm.)
• Set the central knob of the multimeter to the lowest resistance value in the meter. At the same time, connecting the meter probe in a forward bise to the diode. (i.e the positive probe to the anode and the negative to the cathode.)
• Observe the reading in the meter. If the meter reads a low resistance value. It was that diode is good and not faulty.
• Reset the knob to a high resistance value in the meter and reverse the connection. (i.e connecting the positive to the cathode and the negative to the anode).
• If the meter indicates a high value of resistance. It indicates the diode is in its perfect condition and not faulty.

Testing a PN diode using a digital multimeter DMM

The following steps are to follow when testing a diode using a digital multimeter.

• Get a digital multimeter DMM and connect the probes properly. The red to V- ohm and the black to Com. And turn ON the DMM
• Select and position the central knob to diode mode where the diode symbol is in the DMM. In this mode, the DMM is capable of supplying the biasing current of approximately 2mA to the diode.

• connect the lead of the multimeter and measure the diode.

When the reading is between the range of 0.6 to 0.7, then it signifies the diode is perfect and ok. Only for a silicon diode. Whereas, if the diode is germanium it should be in the range of 0.23 to 0.3.
• Revise the connection, (i.e connect the positive probe to the cathode and negative probe to anode).

Checking the readings in the meter. If it displays OL or no value. That means the diode is an open circuit therefore, no current flow through then in reverse bise mode. Therefore, Signifying that the diode is good and healthy.

How to test a zener diode using multimeter meter

Zener diode is basically the same as PN junction diode. Which are specially design to have a low pre-determine reverse breakdown voltage that makes advantage of it’s the high reverse voltage.

The following steps is to follow, when testing a Zener diode.

• Identifying the polarity of the Zener diode.

The more zen diode has two terminals, the anode, and the cathode. The Anode side has a black rig mark in the body of the diode while the other side is the cathode.

• Connect the circuit as shown above.
• position the meter knob to voltage mode in the multimeter.
• Place meter probes across the diode, as shown in the figure.
• Gradually vary the voltage and carefully watch the multimeter, as you are increasing the voltage. The input voltage is increasing and the meter reading is increasing, respectively. Until the diode reaches its breakdown voltage. At this point, the readings in the meter will be constant in respective of the increase in input voltage. If it works like that it means the diode is ok. But if otherwise, it Signifies the diode is faulty.

Let’s say for instance. 12v is applied to a Zener diode, (with a breakdown voltage of 6v) from a battery or any DC source through a resistor. The readings in the meter must be approximately 6v if the Zener diode is good and healthy.