Zener diode, resistor, variable dc power supply, milliammeter. Refer to the voltage reference circuit to set the resistance r 1. A typical zener diode shunt regulator is shown in figure 2. In a dc circuit, zener diode can be used as a voltage regulator or to provide voltage reference. The above circuit is the perfect setup to make a zener diode voltage regulator. We use zener diodes for voltage regulation and voltage stabilisation. The result is that the voltage across the diode and the resistor remains constant. Zener diodes are manufactured with a great variety of zener voltages vz and some are. During the negative swing of the ac voltage however, the zener diode behaves just like the normal diode and clips the output voltage at 0. When the voltage is equal to the breakdown voltage, some current passes through the resistor, the rest passes through the diode. To study and measure the effects of forward and reverse bias on the zener diode current. Pdf performance of shunt voltage regulators based on zener.
While regular diodes get damaged when the voltage across them exceeds the reverse breakdown voltage, zener diodes work exclusively in this region. Zener diode as a voltage regulator linkedin slideshare. The purpose of this experiment is to investigate the application of a zener diode for voltage regulation and also diode applications in clipping and clamping circuits. Zener diode is a reversebiased heavilydoped pn junction diode which operates in the breakdown region. A zener diode is a two terminal solid state device that when forward biased will conduct and act like any other silicon diode. It is different from others diodes zener diodes will also allow current to flow in the reverse direction when the voltage is above a certain value. To construct a zener voltage regulator and experimentally determine the range over which the zener maintains a constant output voltage. The experiments in this laboratory exercise will provide an introduction to. So there are some questions arise that how zener diode regulate voltage and why zener diode regulate voltage in reverse bias, not in.
Zener diodes as voltage regulators a circuit diagram symbol for a zener diode. Zener effect dominates at reverse voltages less than 5 volt whereas avalanche effect dominates above 5 v. Link for the theoretical part of zener diode as voltage regulator. Zener diode as a voltage regulator zener diode is a silicon semiconductor with a pn junction that is specifically designed to work in the reverse biased condition. This voltage difference is called a dropout voltage and can be as much as 0. Note down the corresponding input voltage and output voltage and tabulate it. The zener diode working principles and its various.
Zener diode is a special purpose diode that is used in reverse biased to regulate voltage across it. To regulate or vary the output voltage of the circuit. Zener diode is used in electrical as well as an electronic circuit for voltage regulation. In this video, the examples based on the zener diode circuit have been solved. Iv characteristics of zener diode make it suitable for application such as a voltage regulator. In the above circuit the zener diode of zener voltage v z is connected across the load r l in reverse condition. A simple zenerdiode voltage regulator in the voltage regulator the zenerdiode operates in the breakdown region, which ensures approximately constant voltage across it. The function of a regulator is to provide a constant output voltage to a load connected in parallel with it in spite of the ripples in the supply voltage or the variation in the load current and the zener diode will continue to regulate the voltage until the diodes current falls below the minimum i z min value in the reverse breakdown region. Note that in a transistor the current required by the base is only 1hfe times the emitter to collector current. The stabilised output voltage is always selected to be the same as the breakdown voltage v z of the diode.
Regulator eliminates ripple by setting dc output to a fixed voltage. Generally, a normal diode with p and n junction will not function or blocks the flow of the charge carriers results in no flow of the current is seen during the reverse biasing of the device. The zener breakdown voltage is the minimum reverse biased voltage below which the diode blocks the reverse current. Zener diodes are manufactured with a specific breakdown zener. A zener diode is a diode that breaks down at a specific voltage when it is reverse biased. The critical parameter of this type of diodes is the zener breakdown voltage. Change the rheostat value from maximum to 0 by the interval 100. To construct a zener diode voltage regulator and measure its line and load regulation. One of the most important applications of zener diode is voltage regulation. But when it is reverse biased above a certain voltage known as zener breakdown voltage or zener voltage or avalanche point or zener knee voltage the voltage remains constant for a wide range of current clarence zener is the scientist who discovered this electrical property and the device is. Zener diode is a pn junction diode specially designed to operate in the reverse biased mode. There are many ways in which zener diodes or voltage reference diodes can be used.
If source voltage vs can vary from 20 volt to 30 volt,find the maximum and minimum current in the diode. The most widely known is as a voltage reference in some form of voltage regulator, but they can also be used as waveform limiters for circuits where it may be necessary to limit the excursion of a waveform to prevent overload, etc. Since the zener voltage is constant, the increase in v o causes v be to decrease. Career point cares zener diodes are a special kind of diode which permits current to flow in the forward direction. Excess voltage protection is done by using zener diodes because there will be. The examples are related to the zener diode voltage regulator circuits. The zener breakdown voltage is the minimum reverse biased voltage below which the diode blocks the reverse. Pictured above is a very simple voltage regulator circuit requiring just one zener diode and one resistor. For this particular example, a 20v input voltage was used and the output voltage on the positive swing was 6. Diodes and diode circuits tlt8016 basic analog circuits 20052006 11 3. Related experiments with tl431a shunt regulator a type of variable zener diode.
In our previous articles, we explain in detail about diodes, pn junction diode, semiconductors etc. Zener diodes are used in circuits to maintain a fixed voltage across a load. It maintains a constant voltage across the device, so it is typically employed as a simple voltage regulator in many circuits. If you ignore the fact im switching the 1wire on and off,, the upper 3. A zener diode is one of the specially designed diodes that predominately works in reverse biased conditions. September 25, 2019 by watelectronics leave a comment. Building a voltage regulator with an ideal zener diode, construction of a voltage regulator is easy, simply connect the diode between the unregulated voltage and ground. These conditions destroy normal diodes, but a zener conducts a small amount of current. They are more heavily doped than ordinary diodes, due to which they have narrow depletion region. As long as the input voltage is a few volts more than the desired output voltage, the voltage across the zener diode will be stable. Observe the e ects load resistance on parallel voltage regulation zener diode and series voltage regulation ic regulator. Zener diode as a voltage regulator working principles. To design and test a simple zener voltage regulator component equipment required. A voltage regulator is designed to automatically regulate voltage level.
Zener diode, resistors, power supply, multi meter circuit diagram. In this experiment, we try to observe the relation between the voltage and. Zener diode is a pn junction diode specially designed to operate in. Coed school kolar road bhoapl department of physics project report investigatoryproject on pn junction and diodes project report submitted by govind patel submitted to mrs ratna hajela. Study of zener diode as a voltage regulator diode volt free 30. They provide a lowcost and no frill method for voltage regulation.
To study and draw the characteristics of half wave and full wave rectifiers. The figure below shows the circuit arrangement of zener diode as a regulator. The zenor diode is used as a regulator to drop the voltage to 3. A zener diode is manufactured for lower and exact reverse break down voltage. The reverse breakdown of a pn junction may occur either due to zener effect or avalanche effect. These voltage regulators are available in the form of ics. After the fact that it exhibits the zener effect, that is a specific type of voltage break down, so the diode is called zener regulator. A zener diode regulates the voltage drop across a load resistor at 4. To study and draw the characteristics of rectifier filter circuit. Voltage regulators procedures and explanations 1 zener diode shunt voltage regulator when an ideal diode is reverse biased, it conducts no current.
A zener diode is a type of diode that allows current to flow in the conventional manner from its. The depletion layer at the reverse biased pn junction acts like an insulator1. Zener diode working, characteristics and application as. When forward biased, it behaves like a normal signal diode, but when the reverse voltage is applied to it, the voltage remains constant for a wide range of currents.
Zener diodes are used in voltage regulation in circuits because even. Zener diode makes for a lousy regulator bald engineer. This particular zener diode in use has a breakdown voltage of 5. Zener diode as voltage regulator and its vi characteristics. In this video you will get full experimental information about zener diode and zener diode as voltage regulator. The zener diode is used to regulate the base voltage which leads to regulated emitter voltage. Since the exploited property of zener diodes is the reverse breakdown voltage, connect the anode of the diode to ground, not the cathode. The main use of zener diode lies in the fact that the voltage across a zener diode remains constant for a larger change in current. Voltage regulation the purpose of a voltage regulator is to maintain a constant voltage across a load regardless of variations in the applied input voltage and variations in the load current. Applications of zener diodes voltage regulator, meter. Observation of characteristics of a zener diode debangshu mukherjee bs.
Study of zener diode as a voltage regulator free download as pdf file. Fix the load resistance value by using load resistance slider. Transistor series regulator since q 1 is an npn transistor, v o is found as. This means that when outputting 5 v at 150 ma, the input terminal of the regulator needs to be at 5. Zener diode as voltage regulator experiment youtube. The breakdown voltage of a zener diode is deter mined by the resistivity of the diode. It provides a constant voltage to the load from a source whose voltage may vary over a sufficient range. In this part, limiting circuit is described in figure 1 above. Plot the graph in which v in at xaxis v l at yaxis. A voltage regulator is a circuit used to maintain a constant output voltage at a. In a zener diode voltage regulator circuit,the source series resistance rs 20 ohm. To plot and study the input and output characteristics of bjt in.
To design series and shunt voltage regulator experiment 11. This makes sure that even when a load is applied the voltage doesnt drop. If load resistance increases, load voltage also increases. A zener diode is a diode designed to operate in the breakdown region.
It basically steps down the input voltage to the desired level and keeps that in that same level during the supply. The objective of this lab activity is explore the use of zener diodes to build a. Voltage regulators,circuits,types,working principle. Design for an opamp voltage regulator circuit to drive a load of 6v,1. This breakdown voltage is known as the zener voltage. The decrease in v be reduces conduction through the pass transistor. The zener diode mainly operates in reverse biased condition. Zener diodes voltage regulator, diodes clippers and clampers. Basic electronics notes on vi characteristics of zener. A voltage stabilizer is a combination of elements that are designed to ensure the output voltage of a supply fairly remains constant. The zener voltage regulator consists of a current limiting resistor r s connected in series with the input voltage v s with the zener diode connected in parallel with the load r l in this reverse biased condition. The aim of the laboratory work is to understand the principle of zener diode operation and also apply the knowledge practically by completing laboratory tasks.
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