Diode Limiter

The diode limiter also called Clipper as it is used to limit the input voltage.when the positive cycle of the input wave comes, the diode becomes forward biased (fig. 2). As the cathode now at zero volts 0 v,the anode cannot exceed 0.07 volts assuming diode is a silicon diode.

So it limited to 0.7 volts as positive cycles comes from input voltage.When negative cycle comes the diode become reverse biased and at the output load we only get the negative cycle with clipped positive cycle.

And if we put the diode in reverse we will get the positive cycle with the clipped negative cycle
as shown below in the figure.





Figure 1: Shows the input
Figure 2: positive cycle clipped.
Figure 3: Negative cycle clipped.
Figure 4: Both the positive and negatice cycles are clipped. Read More!

P Type Semiconductors

When the trivalent impurity atoms like aluminium (Al), boron (B), indium (In) and gallium (Ga) having three valence electrons are added to silicon,after forming covalent bond one hole remains in silicon which need fourth electrons.As much as impurities atoms added more holes are produced called majority carriers.
The number of holes can be controled by impurites atoms added to silicon.The majority of current carriers is P-type material.There are also some free electrons produced when electron holes are thermally treated.These electrons are the minority carriers in p-type material. Read More!

N Type Semiconductors

Doping:

The conductivity of silicon and germenium can be drastically increased by the controlled addition of impurities to the intrinsic (pure) semiconductor material. This process, called doping, increases the number of current carriers (electrons or holes).

N Type Semiconductor:

To increase the number of conduction band electrons , pentavalent impurity atoms like arsenic (As), phosphorus (P), bismith(Bi) and antimony (Sb) are added.
Each pentavalent atom leaves an extra free conduction electron after combining with the silicon atom forming covalent bond.As pentavalent atom gives an electron so called donar atom.
The number of conduction electrons can be controled by the impurities ato added to silicon.

Most of current carriers are electron,silicon doped with pentavalent atoms is an n-type semiconductor material.The electrons are called majority carriers.There are also some holes when electrons are paired when thermally processed.These holes are called minority carriers. Read More!

Inductors

Inductors store energy in a magnetic field. The magnetic field is created by passing current through a coil of wire, as is done in an electromagnet such as those used to lift scrap iron.
In electric circuits inductors often play the role of smoothing devices that reduces current variations.But when the current is forced to change abruptly, the inductor generates a large induced voltage- - large enough to cause a spark in the extreme case of an automobile ignition circuit.
This two terminal device consists of a wire coil wound around a core.The core may be cylindrical or it may be doughnut-shaped. The coil has N turns , insulated from one another and from the core.When the wire carries the current i, a magnetic field is created in the space around the coil and becomes concentrated within the core.Like an electric field, the magnetic field holds energy that comes from the source that established the field.hence,

An inductor stores energy in a magnetic field produced by current through a wire coil.The strength of the field expressed in terms of magnetic flux through the core.The proportionality constant L is the inductance which is measured in henrys (H).

V=L* di/dt Read More!

CAPACITORS

Capacitors store energy in an electric field. The electric field is created by displacing positive and negative charges such that they tend to attract each other.

In electric circuits, capacitors are used to store energy for flash lamps, to provide a tuning mechanism for radios, and to perform various other useful tasks.


This device consists of two metallic surfaces or plates separated by a dielectric.Ideally , the perfect dielectric is insulator,so that it prevents charge flow inside the capacitor.

When a voltage source is attached to a capacitor an electric field is created between the plates. This field holds the energy supplied by the source to move the charges.so

A capacitor stores energy in an electric field produced by displaced charge on the plates.Mathematically,

q= C v where the proportionality constant C is called the capacitance,defined as

C= q/v

Capacitance is measured in farads(F),named in the honour of English experimentalist Michael Faraday(1791-1867).

TYPES OF CAPACITORS:
Capacitors come in a wide variety of shapes and sizes.Particular families are categorized according to the type of dielectric material.some capacitors often consist of thin ceramic disks with metal coatings on the plat surfaces to from the plates.
Larger capacitances are achieved by rolling sheets of metal foil and flexible dielectric into a tubular shape.The dielectric is usually a plastic film such as mylar.


For,
Air variable capacitor's capacitance is 10-500 pF, voltage is 500 and RC is Infinity.
Ceramic disk capacitor's capacitance is 5 pF-50 nF, voltage is 600-1000 and RC is 1000.
Plastic film capacitor's capacitance is 1 nF-5 uF, voltage is 100-600 and RC is 100,00.
Electrolytic capacitor's capacitance is 1 uF-1 F, voltage is 6-250 and RC is 50-500.



Read More!

Full Wave Rectification

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 DC (direct current), and is more efficient.

Full wave rectification:





The positive half cycle:

During the positive half cycle of the supply, diodes D1 and D2 conduct in series while diodes D3 and D4 are reverse biased and the current flows through the load as shown below








The negative half cycle:

During the negative half cycle of the supply, diodes D3 and D4 conduct in series, but diodes D1 and D2 switch of as they are now reverse biased. The current flowing through the load is the same direction as before.



Full wave rectification for smoothing DC:

With the full wave rectification we get the pulsating DC with the ripples.For smooth DC we use capacitors to remove ripples.





Read More!

Half Wave Rectification

In half wave rectification, 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.Half wave rectification can be achieved with a single diode in a one phase supply, or with three diodes in a three-phase supply.

During the first half cycle of the waveform the diode is forward biased and current flows around the circuit formed by the diode, the transformer winding and the load.
During the second half cyclethe diode is reverse biased and no current flows.
The diode only conducts on every other half cycle. Hence, HALF-WAVE RECTIFICATION.
The rectified voltage is DC (it is always positive in value). However, it is not a steady DC but PULSATING DC. It needs to be smoothed before it becomes useful.

Read More!

Rectifier & Inverter

The Electric device which converts the alternating current AC to direct current DC is called rectifier. And this process is known as rectification.
Rectifiers are used in the detection of signals and in power supplies.

&

The electric device which converts the direct current DC to alternating current AC is called Invertor. Read More!

SemiConductors

A semiconductor is a solid material that has electrical conductivity in between a conductor and an insulator; it can vary over that wide range either permanently or dynamically.

Semiconductors are important in electronic technology. Semiconductor devices, electronic components made of semiconductor materials, are essential in modern consumer electronics, including computers, mobile phones, and digital audio players. Silicon is used to create most semiconductors commercially, but dozens of other materials are used Read More!

Conductors & Insulators

CONDUCTORS:
In science and engineering , a conductor is a material which contains movable electric charges. In metallic conductors, such as copper or aluminium, the movable charged particles are electrons.

Positive charges may also be mobile in the form of atoms in a lattice missing electrons (called "holes") or ions, such as in the electrolyte of a battery.

INSULATORS:
Insulator is a material that resists the flow of electric current. An insulating material has atoms with tightly bonded valence electrons. These materials are used in parts of electrical equipment, also called insulators or insulation, intended to support or separate electrical conductors without passing current through themselves. Read More!

Atomic Structure

An atom is the smallest particle of an element that retains the characteristics of that element.Each of the known 109 elements has atoms that are different from the atoms of all other elements.

According to the Bohr model, atoms have a planetary type of structure that consists of central

nucleus surrounded by orbiting electrons .The nucleus consists of positively charged particles called protons and uncharged particles called neutrons .The basic particles of negative charge are called electrons.

A look of helium atom is:


Read More!