Friday, 31 January 2014

Types of Capacitor-Variable value capacitors

A variable capacitor is a special type of capacitor, most commonly used for tuning radios, which allows the amount of electrical charge it can hold to be altered over a certain range, measured in a unit known as farads. Regular capacitors build up and store an electrical charge until it's ready to use. While a variable capacitor stores the charge in the same fashion, it can be adjusted as many times as desired to store different amounts of electricity.
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When altering a variable capacitor, the user is actually changing its capacitance. Capacitance means the amount of energy the capacitor can store. A bigger capacitance means more stored energy. This energy is measured in farads, but because a variable capacitor typically has a very small capacitance, a smaller unit known as a picofarad is used instead. 

Types of Variable Capacitor

Air-gap capacitors:

These capacitors use air as the dielectric medium. The distance between the plates can be varied to change the capacitance. The capacitance values offered are high and can be used with high voltages. These are used for high frequency operations in communication systems.

Types of Capacitor-Constant value capacitors

Ceramic Capacitors
The non – polarized type ceramic capacitors which are also known as ‘Disc capacitors’ are widely used these days. These are available in millions of varieties of cost and performance. The features of ceramic capacitor depend upon:
Type of ceramic dielectric used in the capacitor which varies in the temperature coefficient and Dielectric losses

These are made by placing silver coated ceramic plates on two sides and assembled together to form the capacitor. The surface mount version consists of the ceramic dielectric in which a number of interleaved precious metal electrodes are contained. This structure gives rise to a high capacitance per unit volume. The inner electrodes are connected to the two terminations, either by silver palladium (AgPd) alloy in the ratio 65 : 35, or silver dipped with a barrier layer of plated nickel and finally covered with a layer of plated tin (NiSn).

The typical values range from 10pF to 1uF. The capacitance values are labeled by three digit codes where the first two digits represent a number and the third digit is the multiplier digit.
For example:  104 which is 10*104 pF which is 0.1uF
The tolerance is indicated by a letter like j=5%, K=10% and M=20%.

These capacitors are commonly used as a timing element in filter circuit and balancing oscillator circuits in radio frequency applications, coupling and decoupling networks.

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Types of Capacitor
Types of Capacitor-Constant value capacitors
Types of Capacitor-Variable value capacitors

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Types of Capacitor

Types of Capacitor

Capacitor is an electronic component that stores electric charge. The capacitor is made of 2 close conductors (usually plates) that are separated by a dielectric material. The plates accumulate electric charge when connected to power source. One plate accumulates positive charge and the other plate accumulates negative charge.
The capacitance is the amount of electric charge that is stored in the capacitor at voltage of 1 Volt.
The capacitance is measured in units of Farad (F).

Note:The capacitance is dependent upon the surface area of the plates, the distance between the dielectric medium and the dielectric constant of the object. The greater the area of the plates, the closer they are together and greater the value of the dielectric constant the greater is the value of capacitance.
The capacitance of a capacitor is also affected by the shape or structure of the capacitors.

Types of capacitors:

Wednesday, 29 January 2014

Testing Diodes/LED (Light Emitting Diodes) Using Digital Multimeter - Electronics LAB

Although you can easily test an LED by connecting it to a circuit and seeing if it will light up, you can also use a multi-meter with a diode test function to test an LED and discover a few more things about it too.
  1. Connect the black lead to the COM terminal on the multimeter. 
  2. Connect the red lead to the Ω terminal, unless your particular model differs. 
  3. Turn the dial to the diode symbol on the multimeter. This allows for electric current to travel in one direction (the arrow) and not the other.
  4. Turn the multimeter on. The display window should indicate either 0L or OPEN. 
  5. Choose a regular red LED.
You may like our Multimeter related Posts
Testing AC Voltage
Testing DC Voltage
Testing Continuity
Testing Resistors
Measuring Current
Testing Diodes/LED (Light Emitting Diodes)

Measuring Current Using Digital Multimeter - Electronics LAB

Multimeter has different procedure for measuring current. Current can be measured in the range of milliamperes (400mA max.) to Ampere (10A max.) as shown in the above image

Multimeter works like an ammeter when ammeter.


A.Turn the knob on the DCA section.
B.Choose the current rating. The meter will display current in both rating.
C.Connect the testing leads to the current measurement setting.

Testing Resistors Using Digital Multimeter - Electronics LAB

Multimeter: Testing Resistors

Resistance on your electronic circuit is measured in ohms, represented by the Greek letter Omega (Ω). Measuring resistances is similar to measuring voltages, with a key difference:

You must first disconnect all voltage sources from the circuit whose resistance you want to measure. That's because the multimeter will inject a known voltage into the circuit so that it can measure the current and then calculate the resistance. If there are any outside voltage sources in the circuit, the voltage won't be fixed, so the calculated resistance will be wrong.

For More info and material please visit:

Steps for measuring resistance in the simple circuit:
A.Remove the battery. 

B.Just unplug it from the battery snap connector and set the battery aside. 

Testing DC Voltage Using Digital Multimeter - Electronics LAB

Multimeter: Testing DC Voltage

A simple circuit that glows an LED when connected to power supply.. Connecting LED directly to the power supply will damage it, hence a resistance of suitable value must be connected in series for its proper operation. Following the standard color convention,red wire serves as the positive connection lead while black one is the common or negative lead. In this tutorial, we will be measuring DC voltage and current in the circuit.

Testing Continuity in Circuit Using Digital Multimeter - Electronics LAB

Multimeters are a very useful tool for diagnosing problems with electrical systems. They are simple to use when you know how! I use my fluke multimeter nearly once a week to try and fix problems with electronic devices at home. One of the most basic uses of a multimeter is to test for continuity. Testing for continuity basically means testing to see if there is an electric connection between two points. If two points are electrically connected they are said to be continuous. This brief guide explains how to use a digital multimeter to find out if there is an electric connection between two points. 

Getting Ready 
Before you test for an electric connection you must do a few things:

- Make sure your multimeter is working. You can test this by brushing the two tips together and verifying that you hear a beep. The manual you received with your multimeter may have more information on testing your multimeter. 

Testing AC Voltage Using Digital Multimeter - Electronics LAB

Multimeter: Testing AC Voltage

A.Choose active alternating current socket.

B.Turn the multimeter knob to the ACV or AC Voltage section:

To ensure safe operation make sure that the knob is pointing to 400V before connecting the probe to the plug.

Also make sure that the red probe is connected to the ‘V’ and the black probe to the COM as shown in the image given below:

C. Insert the testing probes into the socket.

Sunday, 26 January 2014

Stepper Motor

A Stepper Motor is a brush less, synchronous motor which divides a full rotation into a number of steps. Unlike a brush less DC motor which rotates continuously when a fixed DC voltage is applied to it, a step motor rotates in discrete step angles. 
The Stepper Motors therefore are manufactured with steps per revolution of 12, 24, 72, 144, 180, and 200, resulting in stepping angles of 30, 15, 5, 2.5, 2, and 1.8 degrees per step. The stepper motor can be controlled with or without feedback.

For more related information please refer:
Motor Types-Introduction
DC Motor
AC Motor
Special Types of Motor
Servo Motors

Stepper motors work on the principle of electromagnetism. There is a soft iron or magnetic rotor shaft surrounded by the electromagnetic stators.

Resistors Color Coding

Resistors Color Coding
Carbon-composition and carbon film resistors are too small to have the resistance value printed on their housings. Therefore, bands of colour are used to represent the resistance value.

The first and second band represent the numerical value of the resistor, and the colour of the third band specify the power-of-ten multiplier. The colour bands are always read from left to right starting with the side that has a band closer to the edge.

For carbon-composition and carbon film resistors, the common tolerances are 5%, 10%, and 20%, indicating that the actual value of the resistor can vary from the nominal value by ±5%, ±10% and ±20%. If the band is gold, it specifies a 5% tolerance; silver specifies a 10% tolerance; if no band is present, the tolerance is 20%.

Note that the colour-code system for capacitors is very similar to that of resistors except there is a fifth band representing the temperature coefficient. This band is the first one closest to one end of the capacitor. The other four fall into the same order as mentioned for resistors. In this case, the second, third, and fourth bands are used to determine the capacitance. The fifth band represents the tolerance of the capacitor.

Measuring Resistance of component in circuit Using Digital Multimeter - Electronics LAB

Measuring Resistance - Using Multi Meter

General precautions:
1. Measure resistance when components are not connected in a circuit.
2. Remember to ensure that the circuit under test is not powered on.
3. Ensure capacitors in a circuit under test are discharged.
4. Remember that diodes in a circuit will cause different readings in either direction.
5. Leakage path through fingers can alter readings in some cases.

Types of Resistors-Special Resistors

Types of Resistors-Special Resistors 
Thermistors are special resistors whose resistance changes with the temperature. If the resistance increases with increase in temperature, then it is called positive temperature coefficient (PTC) or posistors. If the resistance decreases with the increase in temperature, then it is called a negative temperature coefficient (NTC).

An NTC can be replaced by a transistor with a trimmer potentiometer. PTCs are mostly used as current limiter for circuit protection. As the heat dissipation of resistor increases, the resistance is increased thereby limiting the current.

Types of Resistors-Variable resistors

Types of Resistors-Variable resistors
Pre-sets and potentiometers are commonly used types of variable resistors. These are mostly used for voltage division and setting the sensitivity of sensors. These have a sliding contact or wiper which can be rotated with the help of a screw driver to change the resistance value. In the linear type, the change in resistance is linear as the wiper rotates. In the logarithmic type, the resistance changes exponentially as the wiper slides. The value is meant to be set correctly when installed in some device, and is not adjusted by the device's user.

The variable can have one or two switches in-built where the resistor operates for the ON state of the switch(s). Such resistors were mostly used for volume control in older TV and radio circuits.
There may also be four-tab variables where the fourth lead is for feedback signal and placed near the first tab. Wire wound variable resistors are used for very precise control of resistance.

Types of Resistors-Fixed resistors

Types of Resistors-Fixed resistors
A.Carbon Composition Resistors
These resistors are cylindrical rods which are a mixture of carbon granules and powdered ceramic. The resistor value depends on the composition of the ceramic material. A higher quantity of ceramic content will result in more resistance. Since the rod is coated with an insulated material, there are chances of damage due to excessive heat caused by soldering.

High current and voltage can also damage the resistor. These factors bring irreversible changes in the resistance power of these resistors. This type of resistor is rarely used nowadays due to their high cost and are only preferred in power supply and welding circuits.

Types of Resistors

Types of Resistors

An electric resistor is a two-terminal passive component specifically used to oppose and limit current.
A resistor works on the principle of Ohm’s Law which states that voltage across the terminals of a resistor is directly proportional to the current flowing through it.
Ohm’s Law: V = IR

where V is the voltage applied across resistor,I is the current flowing through it,and R is the constant called resistance.
The unit of resistance is ohms.

Types of Resistors:
Colour Coding Of Resistances 
Measuring Resistance - Using Multi Meter

Servo Motors

Servo Motors
A servomotor is a rotary actuator that allows for precise control of angular position, velocity and acceleration. It consists of a suitable motor coupled to a sensor for position feedback. It also requires a relatively sophisticated controller, often a dedicated module designed specifically for use with servomotors.Servomotors are not a different class of motor, on the basis of fundamental operating principle, but use servomechanism to achieve closed loop control with a generic open loop motor.

For more related information please refer:
Motor Types-Introduction
Motor Types- DC Motor
Motor Types- AC Motor
Motor Types- Special Types of Motor
Stepper Motor

Servo refers to an error sensing feedback control which is used to correct the performance of a system. Servo or RC Servo Motors are DC motors equipped with a servo mechanism for precise control of angular position. The RC servo motors usually have a rotation limit from 90° to 180°. Some servos also have rotation limit of 360° or more. But servos do not rotate continually. Their rotation is restricted in between the fixed angles.

Applications of Servos
The Servo motors are used for precision positioning. They are used in robotic arms and legs, sensor scanners and in RC toys like RC helicopter, Airplanes and cars.

Motor Types- Special Types of Motor

Motor Types- Special Types of Motor

1. Iron less or core-less rotor motor

Nothing in the principle of any of the motors described above requires that the iron (steel) portions of the rotor actually rotate. If the soft magnetic material of the rotor is made in the form of a cylinder, then (except for the effect of hysteresis) torque is exerted only on the windings of the electromagnets. Taking advantage of this fact is the core less or iron less DC motor, a specialized form of a PM DC motor. Optimized for rapid acceleration, these motors have a rotor that is constructed without any iron core. The rotor can take the form of a winding-filled cylinder, or a self-supporting structure comprising only the magnet wire and the bonding material. The rotor can fit inside the stator magnets; a magnetically soft stationary cylinder inside the rotor provides a return path for the stator magnetic flux.

Motor Types- AC Motor

Motor Types- AC Motor

An AC motor is an electric motor driven by an alternating current (AC).
It commonly consists of two basic parts, an outside stationary stator having coils supplied with alternating current to produce a rotating magnetic field, and an inside rotor attached to the output shaft that is given a torque by the rotating field.
There are two main types of AC motors, depending on the type of rotor used.
For more related information please refer:
Motor Types-Introduction
Motor Types- DC Motor
Motor Types- AC Motor
Motor Types- Special Types of Motor
Servo Motors

Stepper Motor

Motor Types- DC Motor

Motor Types- DC Motor
  1. Shunt DC motor: The rotor and stator windings are connected in parallel.
  2. Separately Excited motor: The rotor and stator are each connected from a different power supply, this gives another degree of freedom for controlling the motor over the shunt.
  3. Series motor: the stator and rotor windings are connected in series. Thus the torque is proportional to I*I  so it gives the highest torque per current ratio over all other DC motors.It is therefore used in starter motors of cars and elevator motors.
For more related information please refer:
Motor Types-Introduction
Motor Types- DC Motor
Motor Types- AC Motor
Motor Types- Special Types of Motor
Servo Motors
Stepper Motor

Motor Types-Introduction

Motor Types-Introduction

A device that produces rotational force is a motor. The very basic principal of functioning of an electrical motor lies on the fact that force is experienced in the direction perpendicular to magnetic field and the current, when field and electric current are made to interact with each other. Ever since the invention of motors, a lot of advancements has taken place in this field of engineering and it has become a subject of extreme importance for modern engineers.


  1. DC Motor
  2. AC Motors
  3. Special Types of Motor

For more related information please refer:

Wednesday, 22 January 2014

Entry and Exit Counting System for Theaters

"Entry and Exit Counting System for Theaters"

This Project was submitted by group of students of RK College,Rajkot,Gujrat.

This Video was submitted by the group,in which they demonstrate the project.

Group Members:
nilam siddhapara
mansi upadhayay
bordiwala lubna
chachadiya ankita

Monitoring and controlling different industrial appliances using RF communication

This project was done at NSIC Rajkot by the Final Year Engineering students of Om Shanti Engg. college ,Rajkot, Gujrat.

The group is:Monitoring and controlling different industrial appliances using RF communication.
Push raj singh Jadeja
Rana Yogiraj singh
Vandita Sharma
Parth Rawal

This Video was submitted by the group,in which they demonstrate the project.

Wireless Home Automation(Bluetooth)

Hello Everyone ...

Now, since we have completed all concerned projects at NSIC. I am starting a series, in which we will see details of particular projects and students efforts , through these 
snaps and videos available with me.

Wireless control of home appliances By students of R. K college,Rajkot
Sagar naina
Jai makwana 
Mohsin Sumara 
Neel Sanchaniya

This Video was submitted by the group,in which they demonstrate the project.

Thanks & Regards

LCD interfacing with Atmega 32/16 - 4 wire connection

Last time we have given example how to connect LCD with controller as you can see Our Post Interfacing LCD with At mega 16/32.

Now i am introducing concept of four wire data transmission.This way you will be able to save controller pin for another applications.

In above diagram you will see we are using 4 pin of PORTA for data transmission and another 3 pins of same PORT for control lines.In this way we are able to save pins and schematic drawing becomes much more easier.

Anyone who is using ADC for sensors should use other PORTB,C,D rather than PORTA(with same configuration).

Interfacing LCD with At mega 16/32

Here is a new possible way of interfacing LCD with our controller other than what we have done earlier.

About LCD (Liquid Crystal Display 16X2):-
Its screen is an electronic display module and find a wide range of applications. A 16x2 LCD display is very basic module and is very commonly used in various devices and circuits. These modules are preferred over seven segments and other multi segment LEDs.

LCD Complete Tutorials for beginners

The reasons being: LCDs are economical; easily programmable; have no limitation of displaying special & even custom characters (unlike in seven segments), animations and so on.

A 16x2 LCD means it can display 16 characters per line and there are 2 such lines. In this LCD each character is displayed in 5x7 pixel matrix. This LCD has two registers, namely, Command and Data.

The command register stores the command instructions given to the LCD. A command is an instruction given to LCD to do a predefined task like initializing it, clearing its screen, setting the cursor position, controlling display etc. The data register stores the data to be displayed on the LCD. The data is the ASCII value of the character to be displayed on the LCD.

You can connect 8 data pins of LCD to any ports like PORT A/B/C/D. Since we are using Port A for ADC,it is not advisable to connect LCD there. In this particular schematics Pins 33 to 40 are connected to LCD ,but for our projects we will be connecting data pins of LCD on Port C ie. 7 pin on C0 and 14 on C7 and so on.

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