How to Test a Rectifier Diode Using a Multimeter

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A basic semiconductor, in that there’s the presence of two terminals in which one is preferred as the anode and the other as a cathode. It’s created by two different materials called the n-type and p-type. Normally, it’s termed as a p-n junction diode. 

Because it’s application-oriented, it’s also called a rectifier diode. The purpose of that p-n junction is it’s utilized for the conversion of the applied AC into DC. That procedure of conversion is referred to as rectification.

That can be utilized as the basic module in the power supply unit in any electronic appliances where DC is known for powering up the entire device. 

So, what’s a rectifier diode, by the way? 

A rectifier diode is considered a basic semiconductor device utilized in different uses. However, one of its uses includes the conversion of power, which is from low currents into higher currents, which we call rectification. 

The standard symbol of a diode is that composed of both cathode and anode in it’s sufficient to represent it as a diode. The alignment of that diode could be performed in such a manner that it becomes application-oriented. Generally, it can work as a rectifier. 

How Does a Rectifier Diode Work?

A diode is an electrical circuit that functions the same as a rubber valve in a bike tire. The valve enables the pumped air to enter from one side and stops from the other. Likewise, a rectifier diode enables the flower of current through one course only. 

Hence, it is utilized as a polarity guard within electronic circuits to prevent the risks of an incidental reversal of supply voltage.  

Another crucial function of a rectifier diode is rectification or the converting of AC to DC. Remember that the voltage in an alternating current (ACD) turns from positive and negative and vice versa a number of times for every second.

Based on the connection, a rectifier diode will enable only a negative or a positive cycle to pass and stop the other. Hence, the output will either be purely negative or positive. That’s what we referred to as rectification.

That property is well used and exploited in power supplies, battery charges, AC or DC adapters, and more. However, keep in mind that a diode will require a minimum voltage of approximately 0.7 volts across it to efficiently bring on the above procedure of rectification. 

In short, a diode requires approximately 0.7 volts to reasonably start the electricity’s conduction. It’s referred to as the low forward voltage drop of a rectifier diode. 

A diode with its two terminals—formed by the doping of n-type and p-type on a single crystal—has the presence of inbuilt potential in it. The diode is biased if it’s given with some external voltage. That biasing is further categorized as reverse and forward based on the application of external voltage to the corresponding terminals. 

What are the Different Types of a Rectifier Diode?

You will find two types of rectifiers: full-wave and half-wave rectifiers. 

In case you didn’t know, the half-wave rectifier converts half of the AC wave to DC power using as few as a single diode. Meanwhile, full-wave rectifiers convert the full AC wave and can utilize as few as two diodes. 

You will find some varieties on both of such types of rectifiers, like the full-wave bridge rectifier that utilizes as few as two diodes. There are other variations on both of such rectifier types, like the full-wave bridge rectifier that utilizes four diodes. 

  • Full-wave rectifiers

A center-tapped transformer and two diodes make up the circuit in a simple full-wave rectifier. When the positive half of the AC wave passes, one diode enables current flow as in a half-wave rectifier. 

Nonetheless, it travels through the second diode in a reversed polarity when the second half of the wave passes. That way, both the negative and the positive halves of the AC wave are rectified and combined, offering constant current flow.

  • Half-wave rectifiers

This rectifier happens when the diode enables the positive half of the wave to pass through it. The current reverses and the diode stops that portion when the wave reaches its negative half. That makes a kind of on and off pattern where the positive half has current flow, but there’s none during the time it takes for the other negative half of the wave to pass.

Other kinds of devices like capacitors could help average that out. Nonetheless, for most types of devices, that’s adequate rectification. 

What are the Applications of a Rectifier?

Some applications of a rectifier diode are the following:

  • Used in the rectifier circuit as the basic block of rectification 
  • Detection and mixing of signals can also be done by a diode
  • Diodes are applicable during the suppression of spikes in voltage
  • Applicable in voltage multipliers
  • Used in the designing of logic gates to do digital operations

How Do You Test a Rectifier Diode? 

One of the simplest and straightforward ways you can test a rectifier diode is with a digital multimeter. 

Below are the steps you need to follow to test a rectifier diode.

  1. Grab a good-quality digital multimeter and set the range in the diode setting. 
  1. On display, you should see a three (3) or an infinite voltage reading, but that will depend on the multimeter utilized.
  1. Attach the red lead probe to the cathode and the black lead probe to the anode of the diode. 
  1. The display will present the low forward voltage drop or rectifier diode of at least 0.6 volts. 
  1. You can now then reverse the connections. The display will go back to its original reading that will indicate the diode is a great one.
  1. Does your digital multimeter show any reading? Then the diode might be faulty or leaky. On the other hand, a 0000 reading indicates there’s a short. 

There you have it! We hope you fully understand now what a rectifier diode is and how you can test it with a digital multimeter. Share your thoughts with us by leaving your comments below.

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