Kirchhoff's Voltage Law.

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 Kirchhoff's Voltage Law(KVL) is Kirchhoff's second law that deals with the conservation of energy around a closed circuit path. ... His voltage law states that for a closed loop series path the algebraic sum of all the voltages around any closed loop in a circuit is equal to zero.

Explanation;

Gustav Kirchhoff’s Voltage Law is the second of his fundamental laws we can use for circuit analysis. His voltage law states that for a closed loop series path the algebraic sum of all the voltages around any closed loop in a circuit is equal to zero. This is because a circuit loop is a closed conducting path so no energy is lost.

In other words the algebraic sum of ALL the potential differences around the loop must be equal to zero as: ΣV = 0. Note here that the term “algebraic sum” means to take into account the polarities and signs of the sources and voltage drops around the loop.

This idea by Kirchhoff is commonly known as the Conservation of Energy, as moving around a closed loop, or circuit, you will end up back to where you started in the circuit and therefore back to the same initial potential with no loss of voltage around the loop. Hence any voltage drops around the loop must be equal to any voltage sources met along the way.

Kirchhoff’s Circuit Loop;

We have seen here that Kirchhoff’s voltage law, KVL is Kirchhoff’s second law and states that the algebraic sum of all the voltage drops, as you go around a closed circuit from some fixed point and return back to the same point, and taking polarity into account, is always zero. That is ΣV = 0

The theory behind Kirchhoff’s second law is also known as the law of conservation of voltage, and this is particularly useful for us when dealing with series circuits, as series circuits also act as voltage dividers and the voltage divider circuit is an important application of many series circuits.

Kirchhoff’s law.

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In this blog I will be explain Kirchhoff’s law.

Kirchhoff’s current law;

Kirchhoff's laws are two equalities that deal with the current and potential difference in the lumped element model of electrical circuits. They were first described in 1845 by German physicist Gustav Kirchhoff. This generalized the work of Georg Ohm and preceded the work of James Clerk Maxwell.

Explanation;

Kirchhoff's Current Law. Kirchhoff's Current Law (KCL) is Kirchhoff's first law that deals with the conservation of charge entering and leaving a junction. ... In other words the algebraic sum of ALL the currents entering and leaving a junction must be equal to zero as: Σ IIN = Σ IOUT.

This idea by Kirchhoff is commonly known as the Conservation of Charge, as the current is conserved around the junction with no loss of current. Let’s look at a simple example of Kirchhoff’s current law (KCL) when applied to a single junction.

A Single Junction;

The current IT leaving the junction is the algebraic sum of the two currents, I1 and I2 entering the same junction. That is IT = I1 + I2.

Note that we could also write this correctly as the algebraic sum of: IT - (I1 + I2) = 0.

So if I1 equals 3 amperes and I2 is equal to 2 amperes, then the total current, IT leaving the junction will be 3 + 2 = 5 amperes, and we can use this basic law for any number of junctions or nodes as the sum of the currents both entering and leaving will be the same.

The resulting equations would still hold true for I1 or I2. As I1 = IT - I2 = 5 - 2 = 3 amps, and I2 = IT - I1 = 5 - 3 = 2 amps. Thus we can think of the currents entering the junction as being positive (+), while the ones leaving the junction as being negative (-).

Then we can see that the mathematical sum of the currents either entering or leaving the junction and in whatever direction will always be equal to zero, and this forms the basis of Kirchhoff’s Junction Rule, more commonly known as Kirchhoff’s Current Law, or (KCL).

 Kirchhoff current law for dc circuits;

Kirchhoff’s current law for parallel circuits;

Parallel Circuits Recall that two elements are in series if they exclusively share a single node (and thus carry the very same current). ... Kirchhoff's Current Law (KCL) Kirchhoff's Current Law states that the algebraic sum of the currents entering and leaving a node is equal to zero.

Electronics Circuits

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In this blog I will be introduce you some simple electronics circuits. Discussed below are very helpful for the beginners while doing practice, designing of these circuits helps to deal with complex circuits.

DC Lighting Circuit;

A DC supply is used for a small LED that has two terminals namely anode and cathode. The anode is +ve and cathode is –ve. Here, a lamp is used as a load that has two terminals such as positive and negative. The +ve terminals of the lamp are connected to the anode terminal of the battery and the –ve terminal of the battery is connected to the –ve terminal of the battery. A switch is connected in between wire to give a supply DC voltage to the LED bulb.

Rain Alarm;

This circuit is used in homes to guard their washed clothes and other things that are vulnerable to rain when they stay in the home most of the time for their work. The required components to build this circuit are probes. 10K and 330K resistors, BC548 and BC 558 transistors, 3V battery, 01mf capacitor and speaker.

Working;

Whenever the rainwater comes in contact with the probe in the above circuit, then the current flows through the circuit to enable the Q1 (NPN) transistor and also Q1 transistor makes Q2 transistor (PNP) to become active. Thus the Q2 transistor conducts and then the flow of current through the speaker generates a buzzer sound. Until the probe is in touch with the water, this procedure replicates again and again. The oscillation circuit built in the above circuit that changes the frequency of the tone, and thus tone can be changed.

Touch Sensor Circuit;

The touch sensor circuit is built with three components such as a resistor, a transistor and a light emitting diode. Here, both the resistor and LED connected in series with the positive supply to the collector terminal of the transistor. Select a resistor to set the current of the LED to around 20mA. Now give the connections at the two exposed ends, one connection goes to the +ve supply and another goes to the base terminal of the transistor. Now touch these two wires with your finger. Touch these wires with a finger, then the LED lights up.

Invisible Burglar Alarm;

The circuit of the invisible burglar alarm is built with a photo transistor and an IR LED. When there is no obstacle in the path of infrared rays, an alarm will not generate buzzer sound. When somebody crosses the Infrared beam, then an alarm generated buzzer sound. If the photo transistor and the infrared LED are enclosed in black tubes and connected perfectly, the circuit range is 1 meter.

Working;

When the infrared beam falls on the L14F1 photo transistor, it performs to keep the BC557 (PNP) out of conduction and the buzzer will not generate the sound in this condition. When the infrared beam breaks, then the photo transistor turns OFF, permitting the PNP transistor to perform and the buzzer sounds. Fix the photo transistor and infrared LED on the reverse sides with correct position to make the buzzer silent. Adjust the variable resistor to set the biasing of the PNP transistor. Here other kinds of photo transistors can also be used instead of LI4F1, but L14F1 is more sensitive.

FM Transmitter using UPC1651;

The FM transmitter circuit using UPC1651 is shown below. This circuit is built with UPC1651 IC. This chip is a wide band silicon amplifier that has a frequency response (1200MHz) and power gain (19dB).

Working;

This chip can be worked with 5 volts DC. The received audio signals from the microphone are fed to the I/p pin2 of the chip through the capacitor ‘C1’.Here, in the below circuit capacitor acts as a noise filter.

The modulated FM signal will be available at the pin4 (output pin) of the IC. Here, ‘C3’ capacitor & ‘L1’ Inductor shapes the required LC circuit for building the oscillations. The transmitter frequency can be altered by regulating the capacitor ‘C3’.

Circuits & Chips

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In this blog I will fully describe about integrated circuits and its types which are commonly used.

Integrated Circuits & Chips;

An integrated circuit or monolithic integrated circuit is a set of electronic circuits on one small flat piece of semiconductor material, normally silicon.

Commonly used integrated circuits;

Thousands of different types of integrated circuits (ICs) are available for electronic devices. Most of these were designed for very specific applications. However, many integrated circuits have been designed for general-purpose use and so are used in a wide variety of circuits.

As its name implies, the 555 is a timer circuit. The timing interval is controlled by an external resistor/capacitor (RC) network. In other words, by carefully choosing the values for the resistors and capacitors, you can vary the timing duration.

The 555 can be configured in several different ways. In one configuration (called mono stable), it works like an egg timer: You set it, and then it goes off after a certain period of time has elapsed. In a different configuration (called a stable), it works like a metronome, triggering pulses at regular intervals.

Besides the basic 555 chip, which comes in an 8-pin DIP package, you can also get a 556 dual timer, which contains two independent 555 timers in a single 14-pin DIP package. Because many common circuits call for two 555 timers working together, the 556 package is very popular.

Circuit diagram;

741 AND LM324 OP-AMPS;

An op-amp is a special type of amplifier circuit that has many applications throughout electronics. Although there are many different types of op-amp circuits, the 741 and LM324 are the most common.

The 741 is a single op-amp circuit in an eight-pin DIP package. It was first introduced in 1968 and is still one of the most widely used integrated circuits ever made. The 741 is one of those ICs that require both positive and negative voltage.

The LM324 was introduced in 1972. It consists of four separate op-amp circuits in a single 14-pin DIP package. Unlike the 741, the LM324 doesn’t require separate negative and positive voltage supplies.

Circuit diagram;

78XX VOLTAGE REGULATORS;

The 78xx is a family of simple voltage regulator integrated circuits. A voltage regulator is a circuit that accepts an input voltage that can vary within a certain range and produces an output voltage that is a constant value, regardless of fluctuations in the input voltage.

The xx in 78xx represents the actual voltage regulated by the chip. For example, a 7805 produces a 5 V output. The input voltage must be at least a couple of volts over the output voltage, and can be as high as 35 V.

Circuit diagram;

74XX LOGIC FAMILY

One of the primary uses for integrated circuits is for digital electronics, and the 74xx is one of the oldest and still most widely used families of digital integrated circuits. The 74xx family includes a wide variety of chips that provide basic building blocks for digital circuits. You won’t find complete microprocessors in the 74xx family. But you will find circuits such as logic gates, flip-flops, counters, buffers, and others.

Capacitor

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     In this blog I will be describe about capacitor. Its types and features.

Capacitors;

A capacitor is a passive two-terminal electronic component that stores electrical energy in an electric field. The effect of a capacitor is known as capacitance.

Types of capacitor;

Capacitors are used in virtually every electronics circuit that is built today. Capacitors are manufactured in their millions each day, but there are several different capacitor types that are available.

Ceramic capacitor:   As the name indicates, this type of capacitor gains its name from the fact that it uses a ceramic dielectric. This gives the many properties including a low loss factor, and a reasonable level of stability, but this depends upon the exact type of ceramic used. Ceramic dielectrics do not give as high a level of capacitance per unit volume as some types of capacitor and as a result ceramic capacitors typically range in value from a few Pico farads up to values around 0.1 µF.

Electrolytic capacitor:   This type of capacitor is the most popular leaded type for values greater than about 1 microfarad, having the one of the highest levels of capacitance for a given volume. This type of capacitor is constructed using two thin films of aluminium foil, one layer being covered with an oxide layer as an insulator. An electrolyte-soaked paper sheet is placed between them and then the two plates are wound around on one another and then placed into a can.

Plastic film capacitors:   There are two main formats for the construction of plastic film capacitors:

Metallized film:   In this type of film capacitor the plastic film has a very thin layer of metallization deposited into the film. This metallization is connected to the relevant connection on one side of the capacitor or the other.

Film foil:   This form of film capacitor has two metal foil electrodes that are separated by the plastic film. The terminals are connected to the end-faces of the electrodes by means of welding or soldering.

Tantalum:   Ordinary aluminum electrolytic capacitors are rather large for many uses. In applications where size is of importance tantalum capacitors may be used. These are much smaller than the aluminum electrolytic and instead of using a film of oxide on aluminum they us a film of oxide on tantalum. They do not normally have high working voltages, 35V is normally the maximum, and some even have values of only a volt or so.

Silver Mica:   Silver mica capacitors are manufactured by plating silver electrodes directly on to the mica film dielectric. To achieve the required capacitance, several layers are used. Wires for the connections are added and then the whole assembly is encapsulated. The values of silver mica capacitors range in value from a few Pico farads up to two or three thousand Pico farads.

Super cap;   Super capacitors with capacitance levels of a Farad or more are now becoming more commonplace. These super capacitors are generally used for applications like memory hold up and the like.

Inductor

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In this blog I will be describe Inductor types and features.

Inductor;

An inductor, also called a coil, choke, or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it. An inductor typically consists of an insulated wire wound into a coil around a core.

Inductor types based on core;

There are different types of inductors. Depending on their material type they are basically categorized as follows,

Air Core Inductor;

    Ceramic core inductors are referred as “Air core inductors”. Ceramic is the most commonly used material for inductor cores. Ceramic has very low thermal co-efficient of expansion, so even for a range of operating temperatures the stability of the inductor’s inductance is high. Since ceramic has no magnetic properties, there is no increase in the permeability value due to the core material.

Iron Core Inductor;

     In the areas where low space inductors are in need then these iron core inductors are best option. These inductors have high power and high inductance value but limited in high frequency capacity. These are applicable in audio equipment’s. When compared with other core indictors these have very limited applications.

Ferrite Core Inductor;

Ferrites are mainly two types they are soft ferrites and hard ferrites. These are classified according to the magnetic coercively. Ferrite is also referred as ferromagnetic material. They exhibit magnetic properties. They consist of mixed metal oxide of iron and other elements to form crystalline structures . The general composition of ferrites is XFe2O4. Where X represents transition materials. Mostly easily magnetized material combinations are used such as manganese and zinc (MnZn), nickel and zinc (niZn).

Soft Ferrite;

These materials will have the ability to reverse their polarity of their magnetization without any particular amount of energy needed to reverse the magnetic polarity.

Hard Ferrite;

These are also called as permanent magnets. These will keep the polarity of the magnetization even after removing the magnetic field.

Ferrite core inductor will help to improve the performance of the inductor by increasing the permeability of the coil which leads to increase the value of the inductance. The level of the permeability of the ferrite core used within the inductors will depend on the ferrite material. This permeability level ranges from 20 to 15,000 according to the material of ferrite.

Iron Powder Inductor;

These are formed from very fine particles with insulated particles of highly pure iron powder. This type of inductor contains nearly 100% iron only. It gives us a solid looking core when this iron 

power is compressed under very high pressure and mixed with a binder such as epoxy or phenolic. By this action iron powder forms like a magnetic solid structure which consists of distributed air gap.

Laminated Core Inductor;

These core materials are formed by arranging many number of laminations on top of each other. These laminations may be made up of different materials and with different thicknesses. So this construction has more flexibility. These laminations are made up of steel with insulating material between them.

These are arranged parallel to the field to avoid eddy current losses between the laminations. These are used in low frequency detectors. They have high power levels so, they are mostly used at power filtering devices for excitation frequencies above several KHz.

Bobbin based inductor;

These are wounded on cylindrical bobbin so these are named as bobbin based inductors. These are mainly used for mounting on printed circuit boards.

It consist of two types of leads they are axial lead and radial lead. Axial lead means lead exits from both sides of the core for horizontal mounting on PC board. Radial lead means lead exits from both sides of the core for vertical mounting on PC board.

Multi-layer Ceramic Inductors;

The name itself indicates that it consist of multi layers. Simply by adding additional layers of coiled wire that is wound around the central core to the inductor gives multi-layer inductor. Generally for more number of turns in a wire, the inductance is also more.

Film Inductor;

These uses a film of conductor on base material. Thus according to the requirement this film is shaped for conductor application. Film inductors in thin size are suitable for DC to DC converters that serve as power supplies in smart phones and mobile devices.

Variable Inductor;

It is formed by moving the magnetic core in and outside of the inductor windings. By this magnetic core we can adjust the inductance value. When we consider a ferrite core inductor, by moving its core inside and outside on which the coil is wounded, variable ferrite core inductor can be formed.

Coupled Inductors

The two conductors connected by electromagnetic induction are generally referred as coupled inductors. We already seen that whenever the AC current is flowing in one inductor produces voltage in second inductor gives us mutual inductance phenomenon.

Molded inductors;

These inductors or molded by plastic or ceramic insulators. These are typically available in bar and cylindrical shapes with wide option of windings.

Transistor

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In this blog I will be describe about Transistor, It’s types and their features.

Transistor;

A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals for connection to an external circuit.

Different Types of Transistors;

We can say that a transistor is the combination of two diodes it is a connected back to back. There are so many types of transistors 

and they each vary in their characteristics and each has their possess advantages and disadvantages. Some types of transistors are used mostly for switching applications. Others can be used for both switching and amplification. Still other transistors are in a specialty group all of their own, such as phototransistors

Transistor Symbol;

Bipolar Junction Transistor (BJT)

Bipolar Junction Transistors are transistors which are built up of 3 regions, the base, the collector, and the emitter. Bipolar Junction transistors, different FET transistors, are current-controlled devices. A small current entering in the base region of the transistor causes a much larger current flow from the emitter to the collector region. Bipolar junction transistors come in two major types, NPN and PNP. A NPN transistor is one in which the majority current carrier are electrons. Electron flowing from the emitter to the collector forms the base of the majority of current flow through the transistor. The further types of charge, holes, are a minority. PNP transistors are the opposite. In PNP transistors, the majority current carrier is holes.

Field Effect Transistor;

Field Effect Transistors are made up of 3 regions, a gate, a source, and a drain. Different bipolar transistors, FETs are voltage-controlled devices. A voltage placed at the gate controls current flow from the source to the drain of the transistor. Field Effect transistors have a very high input impedance, from several mega ohms (MΩ) of resistance to much, much larger values. This high input impedance causes them to have very little current run through them. (According to ohm’s law, current is inversely affected by the value of the impedance of the circuit. If the impedance is high, the current is very low.) So FETs both draw very little current from a circuit’s power source.

Heterojunction Bipolar Transistor (HBT);

AlgaAs/GaAs heterojunction bipolar transistors (HBTs) are used for digital and analog microwave applications with frequencies as high as Ku band. HBTs can supply faster switching speeds than silicon bipolar transistors mostly because of reduced base resistance and collector-to-substrate capacitance. HBT processing requires less demanding lithography than GaAs FETs, therefore, HBTs can priceless to fabricate and can provide better lithographic yield.

Darlington Transistor

A Darlington transistor sometimes called as a “Darlington pair” is a transistor circuit that is made from two transistors. Sidney Darlington invented it. It is like a transistor, but it has much higher ability to gain current. The circuit can be made from two discrete transistors or it can be inside an integrated circuit. The hfe parameter with a Darlington transistor is every transistors hfe multiplied mutually. The circuit is helpful in audio amplifiers or in a probe that measures very small current that goes through the water. It is so sensitive that it can pick up the current in the skin. If you connect it to a piece of metal, you can build a touch-sensitive button.

 Schottky Transistor;

A Schottky transistor is a combination of a transistor and a Schottky diode that prevents the transistor from saturating by diverting the extreme input current. It is also called a Schottky-clamped transistor.

Multiple-Emitter Transistor;

A multiple-emitter transistor is specialize bipolar transistor frequently used as the inputs of transistor transistor logic (TTL) NAND logic gates. Input signals are applied to the emitters. Collector current stops flowing simply, if all emitters are driven by the logical high voltage, thus performing a NAND logical process using a single transistor. Multiple-emitter transistors replace diodes of DTL and agree to reduction of switching time and power dissipation.

Dual Gate MOSFET

One form of MOSFET that is a particularly popular in several RF applications is the dual gate MOSFET. The dual gate MOSFET is used in many RF and other applications where two control gatesare required in series. The dual gate MOSFET is fundamentally a form of MOSFET where, two gates are made-up along the length of the channel one after the other.

Junction FET Transistor;

The Junction Field Effect Transistor (JUGFET or JFET) has no PN-junctions but in its place has a narrow part of high resistivity semiconductor material forming a “Channel” of either N-type or P-type silicon for the majority carriers to flow through with two ohmic electrical connections at either end normally called the Drain and the Source respectively. There are a two basic configurations of junction field effect transistor, the N-channel JFET and the P-channel JFET. The N-channel JFET’s channel is doped with donor impurities meaning that the flow of current through the channel is negative (hence the term N-channel) in the form of electrons.

Avalanche Transistor;

An avalanche transistor is a bipolar junction transistor designed for process in the region of its collector-current/collector-to-emitter voltage characteristics beyond the collector-to-emitter breakdown voltage, called avalanche breakdown region. This region is characterized by the avalanche breakdown, an occurrence similar to Townsend discharge for gases, and negative differential resistance. Operation in the avalanche breakdown region is called avalanche-mode operation: it gives avalanche transistors the capability to switch very high currents with less than a nanosecond rise and fall times (transition times).

Diffusion Transistor;

A diffusion transistor is a bipolar junction transistor (BJT) formed by diffusing dopants into a semiconductor substrate. The diffusion process was implemented later than the alloy junction and grown junction processes for making BJTs. Bell Labs developed the first prototype diffusion transistors in 1954. The original diffusion transistors were diffused-base transistors. These transistors still had alloy emitters and sometimes alloy collectors like the earlier alloy-junction transistors. Only the base was diffused into the substrate. Sometimes the substrate produced the collector, but in transistors like Philco’s micro alloy diffused transistors the substrate was the bulk of the base.