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Full Wave Rectifier

FULL WAVE RECTIFIER- Center-Tapped and Bridge Rectifier

welcome to this article, In this article, we are going to learn about FULL WAVE RECTIFIER- Center-Tapped and Bridge Rectifier as we Learned about Half-wave rectifiers previously.

Today we are going to study about Full Wave rectifier and their types. so before going to start let me tell you if you have not learned my article on Half Wave rectifier so you must check out that you will understand the basics of rectifiers circuits. so let’s get started.

What is Rectifier Circuit?

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A rectifier circuit is that circuit which performs conversion of AC voltages to DC Pulsating Voltages. So how this Rectifier Circuit Works? I mean how the Full Wave Rectifier circuits work? and why we use Full Wave Rectifier circuits? let’s start our discussion.

A Half-Wave rectifier has very few applications, But the full wave rectifier is the most commonly used rectifier. why is it so? it is because it is mostly used in every type of dc power supplies.

In this section, you will use the same concepts that you learned previously in half-wave rectification article, we will take that concept and expand it to full-wave rectifier working. You will learn about two types of full wave rectifiers.

  1. Center-Tapped Full Wave Rectifier.
  2. Bridge Full Wave Rectifier.

Working of Full Wave Rectifier:

A Full Wave rectifier allows current in unidirectional (one-way) through the load during the entire of the input cycle, whereas a half-wave rectifier allows current through the load only during one-half of the cycle.

The result of full-wave rectification is an output voltage with a frequency twice the input frequency and that pulsates every half-cycle of the input, as shown in given picture below.
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Full wave rectifier block diagram

The number of +ve alternations that make up the full wave rectified voltage is twice that of the half-wave voltage for the same time interval. The average value, which is the value measured on a dc voltmeter, for a full-wave rectified sinusoidal voltage is twice that of the half-wave, as shown in the following formula:
Full Wave rectifier output voltage

Working of Center-Tapped Full-Wave Rectifier

A Center-Tapped rectifier is a type of full wave rectifier that uses two diodes connected to the secondary of a center tapped transformer, as shown in Figure given below. A Centre Tapped Transformer is one whose secondary number of turns are grounded to provide two isolate circuits in secondary of Transformer.

Mostly the Word Centre Tapped is used whenever the circuit is grounded in its center. The input voltage of  Centre Tapped Full Wave Rectifier is coupled through the transformer to the center-tapped secondary. Half of the total secondary voltage appears between the center tap and each end of the secondary number of turns as shown in given figure.

Center Tapped Full wave rectifier

For a positive half-cycle of the input voltage:

The polarities of the secondary voltages are as shown in Figure (a). This makes forward-biases diode D1 and reverse-biases diode D2. The path for current is through Diode 1 and the load resistor, as indicated.

For a negative half-cycle of the input voltage:

The voltage polarities on the secondary are as shown in Figure (b). This makes reverse-biases D1 and forward-biases D2. The current path is through D2 and RL, as indicated. Because the output current during both the positive and negative portions of the input cycle is in the same direction through the load, the output voltage developed across the load resistor is a full-wave rectified dc voltage, as shown below.

Center Tapped Full wave rectifier

Read More: What is the Duty Cycle?

Effect of the Turns Ratio on the Output Voltage

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The output voltage of a center-tapped full-wave rectifier is always one-half of the total secondary voltage less the diode drop, no matter what the turns ratio.output voltage of Center Tapped Full wave rectifier

Peak Inverse Voltage

PIV for Center Tapped Full wave rectifier

Each diode in the full-wave rectifier is continuously changing from forward-biased and then reverse-biased. The maximum reverse voltage that a diode can handle is the peak secondary voltage Vp(sec). The peak inverse voltage across either diode in a full-wave center tapped rectifier is:

PIV for Center Tapped Full wave rectifier

Working of Bridge Full Wave Rectifier

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The bridge rectifier is a best full wave rectifier which uses four diodes that connected as shown in Figure below. When the input cycle is in going for positive alternation as shown in part (a), the diodes D1 and D2 are in forward-biased and they conduct current in the direction as shown.

A voltage is generated across Load Resistor that looks like the +ve half of the I/P cycle. During this period of duration, diodes D3 and D4 are reverse-biased.

When the input cycle of bridge full wave rectifier is going in the negative cycle as in (b), the diodes D3 and D4 are also going in forward bias and they conduct current in the same direction through Load Resistor as during the +ve half-cycle.

when the negative half-cycle is coming for the diode, D1 and D2 are going in reverse-biased. A full-wave rectified output voltage appears across RL as a result of this action.

Bridge Full Wave Rectifier operation

Bridge full wave rectifier Output Voltage

A bridge rectifier with a transformer-coupled input is shown in (a). During the +ve half-cycle of the secondary voltage, diodes D1 and D2 are forward biased. we are neglecting diode drop here.

The same is true when D3 and D4 are forward-biased during the negative half-cycle.

output voltage of Bridge Full Wave Rectifier

As you can see in Figure (b), two diodes are always in series with the RL during +ve and -ve half-cycles. If these diode drops are taken into account, the output voltage is.

output voltage of Bridge Full Wave Rectifier

Bridge Full Wave Rectifier circuit

Peak Inverse Voltage for Bridge Full Wave Rectifier

Since the output voltage is ideally equal to the secondary voltage, If the diode drops of the forward-biased diodes are included as shown in Figure 2–40(b), the peak inverse voltage across each reverse-biased diode in terms of Vp(out) is

PIV of Bridge Full Wave Rectifier

The Peak Inverse Voltage rating for Bridge Full wave rectifier’s diodes is less than that required for the center-tapped configuration.

If we neglect the diode drop, the bridge rectifier requires diodes with half the PIV rating of those in a center-tapped rectifier for the same output voltage.

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Bridge Full Wave Rectifier

This was all about for FULL WAVE RECTIFIER Center-Tapped and Bridge Rectifier if you like this article then appreciate our efforts by doing comment thanks for visiting. check daily for more best articles relative studies and technology.

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half wave rectifier

Half Wave Rectifier- Working and Practical Applications

Half Wave Rectifier

A Half wave rectifier is a Circuit which converts Ac voltages to Pulsating Dc Voltages. Let us Observe how this Half wave rectifier converts Ac voltages to Pulsating Dc, I have illustrated the process below:

The process called half-wave rectification. and the circuit which performs this operation is called Half Wave Rectifier.

Working Of Half Wave Rectifier:

Note that A diode is connected to an ac source and to the load resistor, that makes a half-wave rectifier. here all ground symbols represent the same point electrically.

Let’s examine that what happens during one cycle of the input voltage using the ideal model for the diode. When the alternating input voltage (Vin) goes positive (during Positive Cycle), the diode is forward biased and conducts current through the load resistor, as shown in part (a).

The current which makes an output voltage across the load resistor which is RL, which has the same shape as the +ve half-cycle of the input voltage as you can verify see below.Working of Half Wave Rectifier

Now see here when the input voltage goes -ve during the second half of its cycle, the diode is going in reverse-bias. There is no current there, so the voltage across the load resistor (RL) is 0V or at the ground, as shown in Figure (b).Working of Half Wave Rectifier

The final result is that only the +ve half-cycles of the ac I/P voltage appear across the load. Since the output does not change polarity, it is a pulsating dc voltage in nature with a frequency of 60Hz  (here we are using 60Hz that does not matter you can use 50Hz as well), as shown in part (c).

Working of Half Wave Rectifier

Read More: What is the Duty Cycle?

Average Value of the Half-Wave Rectifier Output Voltage

The average value of the half-wave rectified output voltage is the value you would measure on a dc voltmeter. Mathematically, it is determined by finding the area under the curve over a full cycle, as illustrated in Figure given below, and then dividing by the number of radians in a full cycle.

The result of this is expressed in a given Equation, where Vp is the peak value of the voltage.

This equation shows that the Average value of Half Wave Rectifier Output voltage is approximately 31.8%.

eq Half Wave rectifier

Half Wave rectifier positive pulse

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Effect of the Barrier Potential on the Half-Wave Rectifier Output

As we discussed, the diode was considered an ideal one. When the practical diode model is used with the barrier potential of 0.7 V( Silicon Diode)  taken into account, this is what happens.

During the +ve half-cycle, the input voltage must overcome the barrier potential before the diode becomes forward-biased. This results in a half-wave output with a peak value that is 0.7 V less than the peak value of the input, as shown in Figure given below. The expression of the peak output voltage is.

It is usually more preferable to use the ideal diode model because it neglects the effect of the barrier potential when the peak value of the applied voltage is much greater than the barrier potential (at least 10V). However, we will use the practical model of a diode, taking the 0.7 V barrier potential into account unless stated otherwise.Half Wave Rectifier output

Peak Inverse Voltage (PIV) of Half Wave Rectifier

The peak inverse voltage (PIV ) of Half Wave Recitier is its maximum possible voltage the diode has to withstand, or the diode must be capable of withstanding this amount of continuous reverse voltage. For the diode in Figure given Below, A diode should be rated at least 20% higher than the PIV.

PIV of half wave rectifier

PIV of half wave rectifier

Practical Applications of Half Wave Rectifier

  1. . Half Wave Rectifier can be used to obtain the desired level of dc voltage by using Step up or Step down Transformer.
  1. It is used in soldering iron, Soldering Iron circuit uses Half Wave rectifier and it is also used in mosquito repellent to drive the led.
  2. A half wave rectifier is mostly used as an detector in an AM radio, where the output is not only DC, but an audio signal. The current is so small that there is no advantage to a more complex rectifier.
  3. A Half Wave Rectifier is used in pulse generator circuits, firing circuits.
  4. Half Wave rectifiers are used in Signal demodulation: they can be used to demodulate the amplitude of the modulated signal.
  1. Half wave rectifier is used in voltage doubler circuits.

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