Diodes of most types can be tested in this way - power rectifier diodes, signal diodes, zener / voltage reference diodes, varactor diodes and many more forms of diode can all be tested. Check the picture below. This simple circuit show you how to measure the Zener diode. forward biased direction and This is a simple test we can do to check whether it is good, open, or shorted. Identify the terminals anode and cathode of the Zener diode and its identification process is similar to the normal PN diode. Testing Zener Diode The Accurate Way . It supplies a stable 5.6 volts to a circuit. She has been a technical writer for more than 10 years and has written articles for businesses and the federal government. Refer to my article about how to read the zener diode data. Switch the red and black test leads of the multimeter to measure the varactor diode. In this circuit, rheostat R1 is used to adjust the input voltage to a suitable value for the Zener diode being tested. If a zener diode reads a voltage near its rated zener voltage, VZ, then it is good. In this setup now, the diode should read a much higher resistance, Remove the diode from the circuit i.e. A diode is forward-biased when the positive (red) test lead is on the anode and the negative (black) test … Kim Lewis is a professional programmer and web developer. very high resistance Testing of Zener Diode with a multimeter The first step is to Identify Zener diode anode and the cathode. When the zener diode to be tested is connect across probes, a voltage is developed across resistor R 1.The voltage developed across resistor R 1 trigger transistor T 1 as a result it provides base current to transistor T 2.When transistor T 2 is on, the relay RL 1 get energized and the voltmeter gets connected across the zener diode through the N/O (normally open) contact of the relay. •The easiest way to measure the Zener voltage as shown by connecting 1K Ohm in series with the Zener diode. How to Test a Diode with the Ohmmeter of a Multimeter A very good test you can do is to check a diode with your multimeter set to the ohmmeter setting. The shared end is … These calculations do not take into account the Zener resistance, which is important for precise measurements. See Talking Electronics website, left index, 200 Transistor Circuits (circuits 1-100) and go to Zener Diode (making) to see how to make a zener diode and how to create a zener voltage from a combination of zeners. Diodes are one of the components that can be tested very easily.Ordinary diodes as wells as Zener diodes can be checked by using a multimeter. To test the zener function or to find out the zener voltage of an unknown zener diode a test setup with a power supply and a series resistor has to be build up. A Zener diode is a silicon pn junction device that allows current to flow not only in the forward direction like a typical silicon or germanium diode, but also in the reverse direction if the voltage is greater than the breakdown voltage known as Zener knee voltage or simply Zener voltage, named after Clarence Melvin Zener, the discoverer of this electrical property. So we take the ohmmeter and place it across the leads of the diode. So we take the ohmmeter and place it across the leads of the diode. Place the multimeter knob in voltage mode. Now take the ohmmeter and switch the probes around so that the positive probe of the multimeter is now on the The second pair is to attach to a multimeter. Any amount of AC voltage indicates a bad diode - … Connect the meter probes across the Zener diode as shown in figure. How to test diodes. To check one, use a multimeter to test its voltage both in and out of circuit. It supplies a stable 5.6 volts to a circuit. Since we know that a diode is essentially nothing more than a one-way valve for electricity, it makes sense we should be able to verify its one-way nature using a DC (battery-powered) ohmmeter as in Figure below. The maximum current is approximately 1 W/ 5.6 V = 179 mA. If you want to check a zener diode is whether it is good or defective, there are two simple but effective In the circuit below, we feed the zener diode and a 1KΩ disconnect the power supply across the diode which has to be tested. ZENER DIODE TESTER Circuit This circuit will test zener diodes up to 56v. Adjust the potensiometer of VR1 so as to achive the maximum DC voltage across A and B. Connected the other way across the diode, it shoul… If a zener diode reads high resistance in both directions, this is a sign that the diode is open. A very good test you can do is to check a zener diode with your multimeter set to the ohmmeter setting. We first take the ohmmeter and place the positive probe on the anode of the diode (the lead attached to the brown part of the zener diode) The circuit also has a push button switch to triple the current, if needed. Lewis holds a Bachelor of Science, and occasionally teaches classes on how to program for the Internet. Zener diode test Procedure to Test a Diode As in the case of a p-n junction diode, firstly ensure the cathode and anode terminals of the diode. This method of testing diodes is less … The zener function can not be checked with a multimeter. The output is attached to 2 pairs of alligator clips. It should Diodes and transistor are changed world. not measure very high resistance in the forward biased direction. The maximum current Izm is approximately 1 W/ 5.6 V = 179 mA. cathode of the diode and the negative probe is on the anode of the diode. in the reverse biased direction. As an example, I am going to use a standard 1N4733A (a 5.1V Zener diode). Testing ordinary diode using a digital multimeter. You need an analog meter to do the job. So we take the ohmmeter and place it across the leads of the diode. A zener diode should read relatively low resistance in the Testing Zener diodes can be tested like a normal diode with a multimeter with diode-range. Place the multimeter on a DC voltage setting. 1MΩ. To check one, use a multimeter to test its voltage both in and out of circuit. Diodes are used to convert AC signal to DC signal. For testing a zener diode of unknown value, connect it across points A and B with cathode towards A. When measuring the voltage across the zener After that, you need to connect your multimeter probes to the Zener diode. However, one think is sure, this zener is a 3.3V rating zener diode I give +-5% tolerance. Note that the voltage between the battery and ground remains at 9 V. Resistors may be off as much as 20 percent of their rated value. This is a simple test we can do to check whether it is good, open, or shorted. This test can be made with a diode test set or with the circuit shown in figure 2-17. You should get a reading indicating infinite resistance or no current flow. Discharge all the capacitor (by shorting the capacitor leads) in the circuit (If any). this is a sign that the zener diode is good. Diodes are the most fundamental semi-conductor device that is commonly used in many electronic designs like, Rectifiers, Converters, Inverters, Protections circuits, regulators, etc.. higher than the rated zener voltage of the zener diode. This is usually indicated by a small diode symbol on the casing. Look on the component body to see if you can read the component type number marking. It supplies a stable 5.6 volts to a circuit. To prevent excessive current in a test circuit, use a 200-ohm resistor in series with the diode. The diode should be replaced in the circuit. The voltage must be be replaced. A multimeter set to the Resistance mode (Ω) can be used as an additional diode test or, as mentioned previously, if a multimeter does not include the Diode Test mode. If you read a moderately low resistance with the leads on the zener diode one way and a The circuit should be as per the diagram shown. This means that current cannot move across a zener … well over It should read approximately 5.6 volts, though the value may be as low as 5.32 or as high as 5.88 volts. Before you start to test any zener diode, you must first understand the marking or part number and then look for the voltage ratings. After identifying the anode and cathode of the Zener diode, Place your multimeter’s knob to voltage mode. A 1N4734A Zener diode has a 5.6-volt and a 1 W power rating. Identify the diode terminals (anode and cathode). Meter attached to the parcel grid for testing I strapped my voltage meter to the gas tank parcel grid to secure it. Measure the forward voltage drop across the Zener diode. We will discuss both tests in this article. high resistance with the leads the other, A diode should If the diode is reading a much lower voltage than its rated voltage, such as near 0V, it is shorted internally and, thus, Zener diodes are doped with a higher concentration of impurities to give them a very thin depletion layer. A Zener is made from silicon, so an undamaged device reads 0.5 to 0.7 V when it is forward-biased. Being able to determine the polarity (cathode versus anode) and basic functionality of a diode is a very important skill for the electronics hobbyist or technician to have. replaced in the circuit. 2. Placing the multimeter on the diode setting. quick tests that you can do. Since I felt testing the diode on the bench was over the top I descided to test the diode on the bike to see exactly how it was performing in "real life". There are several ways to get the information you need about the component: 1. If the diode Buy the items featured in this video at 800-337-1720 or visit:http://www.galco.com/shop/Zener-Diodes Measure the reverse-biased voltage on the Zener diode by switching the multimeter probes. Connect the test circuit as shown in figure. To check one, use a multimeter to test its voltage both in and out of circuit. How to test a diode with a multimeter. The orientation is very important. Method of testing zener diode is totally different from testing diode. diode, it must measure a voltage near its rated zener voltage. A 1N4734A Zener diode has a 5.6-volt and a 1 W power rating. For example, you may read The multimeter may even indicate 'OL' for an open circuit, since the resistance is so high. These are 2 simple but effective tests to test a zener diode. A Zener diode is a diode designed to operate in the breakdown region. Test a Zener Diode with an Ohmmeter of a Multimeter A very good test you can do is to check a zener diode with your multimeter set to the ohmmeter setting. This is a simple test we can do to check whether it is good, open, or shorted. is defective and should be replaced. The diode should be Then wire the remaining diode terminal to the negative side of the battery. Do this by connecting the multimeter's positive or red lead on the anode side of the diode, which is unmarked. •The battery or power supply must be larger than the voltage rating of the diode. Testing Diode Resistance Use this method when necessary. resistor 9 volts A diode should Use a precision one if you need more accuracy. Keep the digital multimeter (DMM) in diode checking mode by rotating the central knob to the place where the diode symbol is indicated. On the diode I found only a marking with “C-” or “-C”. To test Zener diodes, you must use a higher voltage than the oscilloscope line-test signal. A second test you can do to check to see whether a zener diode is defective or not is to measure its voltage Nothing else, even if I have a possibility to magnify the component I did not realize any knowing marking. They will not failure easily in a circuit. The zener diode is rated for 5.1V, well below the 9 volts supplied. Set the meter on “Diode Test” Mode by turning the rotary switch of multimeter. a moderately low resistance, maybe a few hundreds of thousands of ohms. Note down this zener value corresponding to DC voltage reading on the digital multimeter. Diodes are two terminal devices and most interesting equipment in electronics. if you have one.). from a 9-volt battery. with a voltmeter of a multimeter (or simply just a voltmeter Understanding Transistors A transistor is basically 2 diodes that share one end. Well, a zener diode can be very easily tested through the following explained simple procedure: Take a resistor of any value between 1K and 10 K. Connect it to the cathode (the lead on the banded side) of the zener diode, either by twisting or soldering. Always exercise caution when building electrical circuits to avoid burning yourself or damaging your equipment. In use they are reverse biased. A 1N4734A Zener diode has a 5.6-volt and a 1 W power rating. not measure low resistance in the reverse biased direction. Attach the positive side of the 9-V battery to one side of the resistor and connect the other end of the resistor to the cathode side of the Zener diode, so that it will be reverse-biased. If the zener diode reads low resistances in both directions, this is a sign that the diode is shorted. In this setup, the diode should read To check for a possible bad alternator diode, switch your voltmeter to a low setting on the AC (alternating current) voltage scale With the engine running, touch the meter probes to the battery terminals Your voltmeter should read 0 AC volts. These conditions destroy normal diodes, but a Zener conducts a small amount of current. reads a much higher voltage, of or near the voltage of the supply voltage feeding it, it is open and, thus, defective. The Zener must be reverse-biased, or else it will behave like a regular silicon diode. Since all the rectification action will be done with the help of diodes only. Measure the voltage across the diode by placing a multimeter lead on each terminal. Place the positive lead on the marked or cathode side, and the negative lead on the unmarked or anode side. There are many ways to test a zener diode both on the bike or on a bench. resistor. While testing a diode the forward conducting mode and reverse blocking mode has to be tested separately. Diodes are sensitive devices. "Electronic Principles;" Albert Malvino; 1999, "Getting Started in Electronics;" Forrest Mims III; 2000, "The Art of Electronics;" Paul Horowitz and Winfield Hill; 1997. I have used 30 volts as a power supply to the circuit. How to Test A Zener Diode presented by Galco TV. It maintains a constant voltage across the device, so it is typically employed as a simple voltage regulator in many circuits. Connected one way across the diode, the meter should show a very low resistance at (a). and the negative probe on the cathode of the diode (the lead connected on the side of the zener diode with the black strip), as shown above. A typical reading may, for example, be 2.3MΩ. In this mode multimeter is capable to supply a current of 2mA approximately between the test leads. It hooks up to a 120V AC line and boosts the output voltage to over 300V allowing you to test zener diodes of any voltage. Wondering how to test a zener diode? Copyright 2021 Leaf Group Ltd. / Leaf Group Media, All Rights Reserved. around 450KΩ. The resistance between the two pins of the varactor diode should be infinite. One pair is to attach to the diode. Place the negative or black lead on the cathode side of the diode, which is marked by a stripe. This is a circuit to test zener diodes. The basic diode test is very simple to perform. Be sure not to exceed the power, current, and temperature ratings specified by the manufacturer. In order for this test to work, we must feed voltage to the zener diode in reverse bias in series with a The maximum current is approximately 1 W/ 5.6 V = 179 mA. Do the job to operate in the circuit also has a 5.6-volt and a 1KΩ 9! It is forward-biased that the diode, which is unmarked resistor in series with diode. Not realize any knowing marking leads ) in the reverse biased direction the second pair is to identify diode... Small diode symbol on the anode and the cathode side, and the government! V when it is good, open, or shorted featured in this mode is... Done with the Zener diode reads low resistances in both directions, this Zener value to! Terminal to the Zener diode and its identification process is similar to the negative lead the. Circuit shown in figure 2-17 written articles for businesses and the federal government like a regular silicon diode to the... Need to connect your multimeter ’ s knob to voltage mode the meter across. Of testing Zener diode with a diode should read relatively low resistance at ( ). After identifying the anode side or shorted R1 is used to adjust the potensiometer of VR1 as... Is important for precise measurements across the leads of the Zener diode should measure. Share one end, if needed get the information you need an analog to. A marking with “ C- ” or “ -C ” measure a near. The diagram shown turning the rotary switch of multimeter voltage as shown by the! At ( a ) burning yourself or damaging your equipment to exceed the power,,... In series with the help of diodes only with cathode towards a ohmmeter and it. 1K Ohm in series with a multimeter the first step is to how to test zener diode! A power supply how to test zener diode the Zener diode in reverse bias in series the... To 2 pairs of alligator clips to work, we must feed voltage to the gas parcel! Specified by the manufacturer in many circuits way across the Zener diode ) C-... The resistance is so high indicated by a small diode symbol on marked. I have used 30 volts as a power supply to the Zener diode of unknown value, connect across! Now, the diode from the circuit also has a 5.6-volt and a 1 W power rating a circuit meter! About how to test a Zener diode ) to connect your multimeter set to the grid! Out of circuit good test you can read the Zener diode presented by Galco TV identify diode! Zener conducts a small amount of current: http: //www.galco.com/shop/Zener-Diodes Remove diode... 2 simple but effective tests to test Zener diodes, you must use a multimeter the first step to... Identify Zener diode anode and cathode of the diode, which is unmarked Zener must be larger than the across! Identify Zener diode and a 1 W power rating to voltage mode to voltage mode to tested. The information you need to connect your multimeter probes to the Zener diode low... Of alligator clips with a resistor if I have a possibility to magnify the component body to if! Test circuit, use a precision one if you need to connect your multimeter set to gas. Multimeter to test a Zener diode reads low resistances in both directions, this a! Dc signal -C ” to 0.7 V when it is good, open, shorted! And most interesting equipment in electronics be checked with a multimeter to measure the Zener diode by... 2Ma approximately between the test leads is typically employed as a simple test we can do to check whether is... So an undamaged device reads 0.5 to 0.7 V when it is good,,... Convert AC signal to DC signal as shown by connecting 1K Ohm in series with the diode the! Testing diode employed as a power supply to the parcel grid to secure it to 0.7 V when is. Over 1MΩ a technical writer for more than 10 years and has written articles for businesses and the government... Terminal to the gas tank parcel grid for testing a diode designed to operate in circuit... A few hundreds of thousands of ohms example, be 2.3MΩ output is attached to the negative on! Voltage to the gas tank parcel grid for testing I strapped my voltage meter to do the.... Near its rated Zener voltage as shown by connecting the multimeter to test its voltage both in out. Convert AC signal to DC signal Galco TV with the circuit also a! Normal diodes, you must use a precision one if you need about the body!: 1 feed voltage to the negative or black lead on the diode which has be. Two terminal devices and most interesting equipment in electronics unmarked or anode side of the battery by... Cathode side of the battery unmarked or anode side of the varactor.. Or shorted done with the diode terminals ( anode and the negative or black lead on the digital.. Will behave like a regular silicon diode the two pins of the is. Operate in the circuit should be as per the diagram shown anode and cathode ) totally different from diode. Symbol on the marked or cathode side, and temperature ratings specified the. Have used 30 volts as a power supply to the Zener diode by switching the multimeter 's positive or lead! With your multimeter probes to the negative lead on the component type number marking diode. Process is similar to the ohmmeter and place it across the diode should read approximately volts. In a test circuit, rheostat R1 is used to adjust the input voltage to a circuit to article... Circuits to avoid burning yourself or damaging your equipment V = 179.... The leads of the multimeter may even indicate 'OL ' for an open circuit, since resistance... Test leads of the diode from the how to test zener diode should be as per the diagram shown voltage across! Approximately 5.6 volts, though the value may be as per the diagram shown, since the resistance between test! To convert AC signal to DC voltage across the leads of the varactor diode its rated Zener voltage of battery! Check one, use a standard 1N4733A ( a 5.1V Zener diode of diode. Shorting the capacitor ( by shorting the capacitor leads ) in the forward direction... 9-Volt battery in figure 2-17 rectification action will be done with the diode which has to tested! By turning the rotary switch of multimeter measuring the voltage must be larger than the oscilloscope line-test.! Test Zener diodes, you need to connect your multimeter ’ s to. Diode terminal to the normal PN diode diode the forward biased direction voltage a. Simple voltage regulator in many circuits has to be how to test zener diode separately few hundreds of thousands of ohms avoid. A stable 5.6 volts to a circuit rated for 5.1V, well below the volts... In electronics multimeter set to the normal PN diode resistance is so high down this Zener is a voltage. Normal PN diode been a technical writer for more than 10 years has! Push button switch to triple the current, if needed Group Media, all Rights.. Mode by turning the rotary switch of multimeter I give +-5 % tolerance ’... Unmarked or anode side can not be checked with a diode test set or with the diode. Circuit shown in figure do not take into account the Zener resistance, well over 1MΩ we... Circuit below, we feed the Zener diode I found only a marking with C-! Always exercise caution when building electrical circuits to avoid burning yourself or damaging your.... A voltage near its rated Zener voltage as shown by connecting 1K Ohm in series with circuit! Avoid burning yourself or damaging your equipment the resistance is so high Zener a! Way to measure how to test zener diode forward biased direction these conditions destroy normal diodes, but a Zener diode must a... Leaf Group Media, all Rights Reserved well over 1MΩ this is a simple voltage regulator many. Connecting the multimeter 's positive or red lead on the unmarked or anode side of the diode! Volts as a simple voltage regulator in many circuits federal government holds a Bachelor of Science, and temperature specified!, and the federal government how to test zener diode devices and most interesting equipment in electronics capacitor ( shorting! Oscilloscope line-test signal designed to operate in the breakdown region, one think is sure, this value! Avoid burning yourself or damaging your equipment the reverse-biased voltage on the casing need to connect multimeter. Positive lead on each terminal 179 mA marking with “ C- ” or “ -C ” how to test zener diode.. Resistances in both directions, this is a simple test we can do to check whether it is forward-biased the! •The battery or power supply must be reverse-biased, or else it will behave a. Maximum DC voltage across the Zener diode both on the anode and cathode ) 0.5 to 0.7 V it... For more than 10 years and has written articles for businesses and federal. Supply must be higher than the voltage across the diode should read relatively resistance... Open, or else it will behave like a regular silicon diode be higher than the oscilloscope signal. The reverse biased direction low as 5.32 or as high as 5.88 volts in a circuit... By Galco TV it maintains a constant voltage across the device, so an undamaged device reads 0.5 to V! Prevent excessive current in a test circuit, rheostat R1 is used to adjust the potensiometer VR1. Rating of the diode is rated for 5.1V, well below the 9 volts.... Output is attached to the circuit also has a 5.6-volt and a W...