#Ic 7800 power.supply series#
Though the current through Zener diode $I_Z$ increases with this, the voltage across Zener diode $V_Z$ remains constant, keeping the output load voltage constant.Ĭase 4 − If the input voltage decreases, the current through the series resistor decreases which makes the current through Zener diode $I_Z$ decreases. This increases the voltage drop across the resistor, i.e. Though the current $I_Z$ through Zener diode increases it maintains a constant output voltage $V_Z$, which maintains the load voltage constant.Ĭase 3 − If the input voltage $V_i$ increases, then the current $I_S$ through the series resistor RS increases. Therefore, $V_o$ also remains constant.Ĭase 2 − If the load current $I_L$ decreases, then the current through the Zener diode $I_Z$ increases, as the current $I_S$ through RS series resistor remains constant. The output voltage Vo depends upon the input voltage Vi and voltage across the series resistor $R_S$. Hence we can consider 4 cases to understand the working of a Zener voltage regulator.Ĭase 1 − If the load current $I_L$ increases, then the current through the Zener diode $I_Z$ decreases in order to maintain the current through the series resistor $R_S$ constant. The Zener diode maintains the voltage across it constant in spite of load variations and input voltage fluctuations. The series limiting resistor $R_s$ limits the input current.
The applied input voltage $V_i$ when increased beyond the Zener voltage $V_z$, then the Zener diode operates in the breakdown region and maintains constant voltage across the load. The following figure shows an image of a simple Zener regulator. This characteristic makes Zener diode a good voltage regulator. When the Zener diode is operated in the breakdown or Zener region, the voltage across it is substantially constant for a large change of current through it. We have already discussed the details regarding Zener diode in BASIC ELECTRONICS tutorial. Zener Voltage RegulatorĪ Zener voltage regulator is one which uses Zener diode for regulating the output voltage. Let us have a look at other important regulator types. The arrangement of them in a circuit will be just as in the following figures. Load Regulator − The regulator which regulates the output voltage to be constant, in spite of the variations in load at the output, it is called as Load regulator.ĭepending upon the type of connection, there are two type of voltage regulators. Line Regulator − The regulator which regulates the output voltage to be constant, in spite of input line variations, it is called as Line regulator. Regulators can be classified into different categories, depending upon their working and type of connection.ĭepending upon the type of regulation, the regulators are mainly divided into two types namely, line and load regulators. The following image gives an idea of what a practical regulator looks like. Need for a Regulatorįor a Power supply to produce a constant output voltage, irrespective of the input voltage variations or the load current variations, there is a need for a voltage regulator.Ī voltage regulator is such a device that maintains constant output voltage, instead of any kind of fluctuations in the input voltage being applied or any variations in current, drawn by the load. A regulator is an important device when it comes to power electronics as it controls the power output. The part of electronics that deal with the control and conversion of electric power can be termed as Power Electronics.
Let us now try to understand what a regulator is and what it does. The next and the last stage before load, in a power supply system is the Regulator part.
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