14-CP-

16(Omega)

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Topic:

Rectification Of Diode

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Diode:

A Diode is the simplest two-terminal unilateral semiconductor device. It allows

current to flow only in one direction and blocks the current that flows in the opposite

direction. The two terminals of the diode are called as anode and cathode.

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History:

Thermionic (vacuum tube) diodes and solid state (semiconductor) diodes were

developed separately, at approximately the same time, in the early 1900s, as

radio receiver detectors. Until the 1950s vacuum tube diodes were more often

used in radios because the early point-contact type semiconductor diodes (cat's-

whisker detectors) were less stable, and because most receiving sets had vacuum

tubes for amplification that could easily have diodes included in the tube (for

example the 12SQ7 double diode triode), and vacuum tube rectifiers and gas-filled rectifiers handled some high voltage/high current rectification tasks beyond

the capabilities of semiconductor diodes (such as selenium rectifiers) available at

the time.

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Rectification:

The conversion of alternating current (AC) to direct current (DC),

this involves a device that only allows one-way flow of electrons.

Types:

1. Half Wave Rectification.2. Full Wave Rectification.

There are two types of rectification.

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Rectifier:

Standard rectifiers can be found regulating the power in computers and the electrical

power in motor vehicles. They can also be used in battery chargers for rechargeable

batteries, computer power supplies and vehicle batteries. Also, while rectifier diodes are

often used for AC to DC conversion, diodes with rectifying characteristics are found in

other uses than in electronics. For example, a diode is used in the detector of radios in

order to perform radio demodulation.

The device which is used for rectification is called

Rectifier.

Uses of Rectifier:

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Application of Diode:

We commonly use today, diodes are also used in public facilities i.e Traffic lights, scoreboards, and vending machines are examples of diode-

dependent devices.

Devices that associate with motion sensors such as ceiling lights and

automatic doors help people see better at night and let people

through buildings without effort from opening a door. These

innovations improve lives of those who are physically challenged.

One of the Major use of diode is in Rectification.

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Half Wave Rectification

The process in which only one half of a cycle of alternating current converts into a

pulsating, direct current is known as Half wave rectification.

Explanation:

In half wave rectification of a single-phase supply, either the positive or negative

half of the AC wave is passed, while the other half is blocked. Because only one

half of the input waveform reaches the output, mean voltage is lower. Half-wave

rectification requires a single diode in a single-phase supply, or three in a three-

phase supply. Rectifiers yield a unidirectional but pulsating direct current; half-

wave rectifiers produce far more ripple than full-wave rectifiers, and much more

filtering is needed to eliminate harmonics of the AC frequency from the output.

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Circuit Diagram with Graph: 11

Full Wave Rectification

The process in which we converts the alternating current into continuous

current and that utilizes both halves of each cycle of the alternating current.

Explanation:

A full-wave rectifier converts the whole of the input waveform to one of constant polarity (positive or negative) at its output. Full-wave rectification converts both polarities of the

input waveform to pulsating DC (direct current), and yields a higher average output

voltage. Two diodes and a center tapped transformer, or four diodes in a configuration

and any AC source (including a transformer without center tap), are needed. Single

semiconductor diodes, double diodes with common cathode or common anode, and four-diode bridges, are manufactured as single components.

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In this circuit both half cycles of AC are used.

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D1

D2

D3

D4

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D1

D3 D2

D4

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While half- and full-wave rectification suffices to deliver a form of DC output, neither

produces constant voltage DC. In order to produce steady DC from a rectified AC

supply, a smoothing circuit is required. In its simplest form this can be what is known as a reservoir capacitor or smoothing capacitor, placed at the DC output of the rectifier.

There will still remain an amount of AC ripple voltage where the voltage is not

completely smoothed.

How to get Smoothing output: 17

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Cro stands for Cathode

Ray Oscilloscope.

This versatile

instrument was

developed by Brown in

1897 from the cathode

ray tube.

USE OF CRO: 19

To get the desirable waveform of voltage ,

current, time period, frequency etc.

Waveform of Half wave rectification:

Waveform of Fulll wave

rectification:

Advantages:

The rectification efficiency of full-wave rectifier is double of that of a half-wave rectifier.

Higher output voltage, higher output power and higher Transformer Utilization Factor in

case of full-wave rectifier.

For a given power output, power transformer of smaller size can be used in case of the bridge rectifier because current in both primary and secondary windings of the supply

transformer flow for the entire ac cycle.

Utilizes both halves of the AC waveform.

Easier to provide smoothing as a result of ripple frequency.

Disadvantages:

It requires four diodes.

The use of two extra diodes cause an additional voltage drop

thereby reducing the output voltage. More complicated than half wave rectifier.

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Conclusion

This experiment show that how we can convert the AC

current/Voltage into DC Current/voltage.

Also how we can Get Smooth output using Capacitor as a Filter.

References

Wikipedia Free Encyclopedia.

Fsc Book part 1st and 2nd .

Radiographic Equipments By Chesney.

Christensen’s Physics For Diagnostic Radiology.

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