What is soldering and when should you use it?

• Soldering is a process in which two or more metal items are joined together by melting and then flowing a filler metal into the joint—the filler metal having a relatively low melting point.
• Soldering is used to form a permanent connection between electronic components.
• The metal to be soldered is heated with a soldering iron and then solder is melted into the connection.
• Only the solder melts, not the parts that are being soldered.
• Solder is a metallic "glue" that holds the parts together and forms a connection that allows electrical current to flow.
• You can use a solderless breadboard to make test circuits, but if you want your circuit to last for more than a few days, you will want to solder the components together.

Materials and Equipment

• A soldering iron
• A soldering iron is used to heat the connections to be soldered.
• For electronic circuits, you should use a 25- to 40-watt (W) soldering iron.
• Higher wattage soldering irons are not necessarily hotter; they are just able to heat larger components. A 40-W soldering iron makes joints faster than a 25-W soldering iron does.
• A soldering iron can be purchased at hardware stores and at most large department stores.
• Rosin core solder
• Solder has a lower melting point than the metals that are being connected do. The solder melts when it is heated by the soldering iron, but the metals being joined will not melt.
• The rosin core acts as a flux. It prevents oxidation of the metals that are being connected, and enhances the ability of the solder to "wet" the surfaces that are being joined.
• Solder that is used to join copper pipes has an acid core, which is appropriate for pipes, but will corrode electronic connections. Use solder that has a rosin core.
• For most electronics work, a solder with a diameter of 0.75 millimeters (mm) to 1.0 mm is best. Thicker solder might make soldering small joints difficult and also increases the chances of creating solder bridges between copper pads that are not meant to be connected.
• An alloy of 60/40 (60% tin, 40% lead) is used for most electronics work, but lead-free solders are available as well.

Multimeter Resistance Test

1. Set the multimeter to read "resistance." Check that the two probes are inserted in the right holes.
2. What does the readout say when the probes are not touching anything? When the two probes are separated, there is an infinite resistance separating them, since air does not conduct electricity. Make a mental note of your multimeter's readout for infinite resistance, because it varies with the manufacturer.
3. Touch the two probes together. Now what does the readout say? When you touch the two probes together, the resistance is close to zero, since the metal tips are excellent conductors.
4. Measure the resistance of some resistors that are not attached to a circuit. For example, test resistors of 100 Ω (ohms), 10,000 Ω, and 1 MΩ (megaohm, or 1 million ohms). You can buy these online at www.radioshack.com. Touch the probes to the wires on either side of the central cylinder. Watch the units: a "k" means kilo-ohms (thousands of ohms), and an "M" means megaohms. Look online for a chart that tells you how to read the value of the resistance based on the colored bands.
5. Never measure resistance in a circuit when power is applied. You must also discharge capacitors in a circuit before measuring resistance, because if there is any source of current other than the multimeter itself, you will get erroneous readings. If the circuit you are working with has large capacitors, you should test them to see if they are carrying a charge. Test the capacitor for charge using a voltmeter, set to high DC voltage. If there is a charge on the capacitor, use a high-wattage resistor to discharge it. Carefully touch the two leads of the resistor to the leads of the capacitor. It may take several seconds for the capacitor to discharge. For more details about how to safely discharge capacitors, visit the following website: Capacitor Testing, Safe Discharging, and Other Related Information

Electronic Terms or Units

AC - Abbreviation for alternating current, which is voltage that flips back and forth between positive and negative.


Ampere - Unit of current (symbol: A).


Breadboard - A board used to make temporary circuits. The breadboard has metal-lined sockets for connecting electronic components in a test circuit.


Capacitor - An electronic component consisting of two conducting surfaces, separated by an insulator. It is used to store and release energy and to control high-frequency signals.


Circuit - A collection of electronic parts connected together, usually designed to perform some kind of function.


Circuit diagram - A diagram that depicts a circuit, using symbols for electronic components. Used to design and communicate circuits with other people, like a blueprint or a plan.


Closed circuit - A circuit in which current can flow through electronic components, from a point of high voltage to a point of low voltage.


Conductance - The opposite of resistance. Materials with high conductance (e.g. metals) have low resistance. The unit of conductance is siemens (S).


Current - The flow of electric charge. The unit for current is amperes (A).


DC - Abbreviation for direct current voltage, which is voltage that does not alternate.


Diode - An electronic component that allows current to flow freely in only one direction.


I - Symbol for current. The unit for current is the ampere (A).


Integrated circuit (IC) - An electronic component that contains several simpler electronic components. An IC is a miniaturized electronic circuit.


Jumper - A short length of wire used to temporarily complete a circuit or to bypass a break in a circuit.


Kilo - A prefix meaning "thousand." A 10-kΩ resistor is 10,000 ohms.


Lead - Length of wire used to make connections between components in a circuit.


Light-emitting diode (LED) - A solid-state device that has two key features: it allows current to flow in only one direction (that is the "diode" part), and it emits light when current flows through it in the "allowed" direction. LEDs are described by several specifications, some of the more important of which are:
Maximum current;
Brightness;
Color of light;
Angle of light beam (for example, an LED with an angle of 15 degrees produces a more focused beam than one with a beam of 45 degrees); and
Size, usually 5 mm.

What is Electronics ?

The field of electronics offers a powerful set of tools for obtaining accurate numerical data. Instead of just saying that there is a difference between two things (color, brightness, charge, etc.), electronic devices allow you to measure precisely how big the difference is.


Electrons and Charge
The word electronics is derived from "electron." Electrons are sub-atomic particles with a negative charge. The unit for electric charge is the coulomb. One coulomb equals the charges of 6.24 billion billion (1018) electrons. A single electron has a charge that is too small to measure in most electronic devices, so scientists use coulombs as a more useful way to describe charge.


Multimeters
The basic outputs for electronic devices are voltage, current, and resistance. Inexpensive and sensitive devices, called multimeters, can measure each of these. If you can devise a way for the output of your experiment to be in the form of voltage, for example, you can use a multimeter to get precise numerical data.


Voltage
The definition of voltage is: the measurement of the potential for an electric field to cause a current in a conductor. An electric field "pushes and pulls" electric charges, so if you put an electron in an electric field, it will move. The movement of charged particles is a current (more about current below). The essential point is that the voltage is a measure of how strongly charged particles are being pushed and pulled by an electric field. The symbol for voltage is V.
Consider a simple flashlight with two D batteries. Each D battery has a voltage of 1.5 V. By putting two 1.5-V batteries together, the total voltage equals 3 V. This voltage is high enough to power a lightbulb. When you turn the flashlight on, the voltage difference causes electrons to flow through the lightbulb, making it shine. The electric field provides the energy to move charged particles through wires (electrical conductors) and through the lightbulb.


Voltage can be direct (DC) or alternating (AC). In DC voltage, the voltage does not alternate. If you graph the voltage of a 9-V battery vs. time, for example, you will have a straight line at a value of 9 V. Alternating current flips back and forth between positive and negative. If you make a graph of AC current vs. time, it will alternate from positive to negative, often in the form of a sine wave. Voltage is supplied to a circuit by a battery or other power supply.


Current
Current is a measurement of how much charge moves through a circuit in a given period of time. In the case of the flashlight, the current through the lightbulb is a measurement of the amount of electric charge flowing through the lightbulb in a given time.
The symbol for current is I. The symbol for the unit of current, the ampere, is A. The precise definition of an ampere is: the current produced by the flow of one coulomb per second. Use "I" when referring to current (as in Ohm's law, discussed below) and "A" when referring to the amount of current.
DC current is produced by DC voltage and AC current is produced by AC voltage.


Resistance
Electrons flow through materials in response to a voltage, creating a current. Some materials, such as copper, have very low resistance, so the electrons flow freely—they are good conductors. Some materials have intermediate resistance, such as the semiconductors used to make transistors. Semiconductors might have a threshold value for the voltage that will cause a current to flow, for example. And some materials, such as rubber, have high resistance and are used as insulators to separate charges.
The symbol for resistance is R. The unit for resistance is the ohm, which has the symbol Ω, and is the capital letter "W" in Greek.


Ohm's Law
Ohm's law relates voltage, current, and resistance, mathematically. Ohm's law can be written as: V = IR. In words, Ohm's law states that the voltage in a component in a circuit equals the current through the component, times the resistance of the component.


Electronic Circuit
An electronic circuit is a closed path formed by the interconnection of electronic components through which an electric current can flow. You might find it helpful to compare an electronic circuit to a circuit in which water flows.
Voltage in the electronic circuit is like the pump in the water circuit—it provides the push to make things go.
Current in the electronic circuit is like the rate (in liters per second, for example) that water flows in the water circle.
And resistance in an electronic circuit is like a constriction in a hose in the water circuit. An electronic resistor impedes the flow of electrons, just as a constriction in a hose impedes the flow of water.

Automation Based Project for ECE Students

 Automation Based Projects
 Auto scheduled dialer Auto gear changer
 Automatic auto transformer based starter
 Automatic college bell
 Automatic control system for rubber industries
 Automatic dam shutter control
 Automatic dim and dipper for automobiles
 Automatic door open
 Automatic drainage timer for compressors
 Automatic electric phase changeover
 Automatic electronic bus fare system
 Automatic grinder controller
 Automatic hand-wash system
 Automatic load sharer for transformers
 Automatic star delta starter
 Automatic steering of farm vehicles using GPS.
 Automatic street light controller with RTC
 Automatic taxi trip sensing & indicating system through GSM
 Automatic timer for cooking
 Automatic traffic and street light controller
 Automatic traffic controller for ambulance and VIP vehicles
 Autonomous navigation of  RFID sensing robots (information ensuring for the visually impaired)
 Auto scheduler for multiple machines
 Invalentary Train Collission Prevention System for Railway
Electronic passport for luggage identification system Door open close using voice

Liquid Crystal Display (LCD)

                                          Short for liquid crystal display, a type of display used in digital watches and many portable computers. LCD displays utilize two sheets of polarizing material with a liquid crystal solution between them. An electric current passed through the liquid causes the crystals to align so that light cannot pass through them. Each crystal, therefore, is like a shutter, either allowing light to pass through or blocking the light.

Monochrome LCD images usually appear as blue or dark gray images on top of a grayish-white background. Color LCD displays use two basic techniques for producing color: Passive matrix is the less expensive of the two technologies. The other technology, called thin film transistor (TFT) or active-matrix, produces color images that are as sharp as traditional CRT displays, but the technology is expensive. Recent passive-matrix displays using new CSTN and DSTN technologies produce sharp colors rivaling active-matrix displays.

Most LCD screens used in notebook computers are backlit, or transmissive, to make them easier to read.

A color television picture tube contains three electron guns, one corresponding to each of the three primary colors of light—red, green, and blue. Electromagnets direct the beams of electrons emerging from these guns to continuously scan the screen. As the electrons strike red, green, and blue phosphor dots on the screen, they make the dots glow. A screen with holes in it, called a shadowmask, ensures that each electron beam only strikes phosphor dots of its corresponding color. The glow of all the dots together forms the television picture.

Difference between microprocessor and microcontroller

Basic block diagram of Microcontroller

Microprocesser

                                                                                                                             T                                         The microprocessor is the integration of a number of useful functions into a single IC package other wise it can be call it as a CPU.At the same time  a microcontroller is obtained by integrating the key components of microprocessor,RAM, ROM, and Digital I/O . Microcontrollers are usually designed to perform a small set of specific functions for example as in the case of a Digital Signal Processor which performs a small set of signal processing functions and it is  widely used to regulate the brakes on all four wheels, or to regulate the car air conditioning .But Microprocesser  performs a wide range of task ie microprocessor in a PC.The basic difference between the microprocessor and Microcontroller is that we can interface a microcontroller directly means "for example we can directly connect a keyboard to microcontroller to any of its ports"....where as for microprocessor we can't interface directly...we require a circuit board since it requires ram,ic's.....etc.,!We can directly interface digital and analog signal for processing.  But it is not the case in the microprocessor.Microprocessor is the device  that does not have memory(internal),in micontroller it has internal memory and has connected directly to pheripheral device.Microcontroller differs from a microprocessor in many ways. First and the most important is its functionality. In order for a microprocessor to be used, other components such as memory, or components for receiving and sending data must be added to it. In short that means that microprocessor is the very heart of the computer. On the other hand, microcontroller is designed to be all of that in one. No other external components are needed for its application because all necessary peripherals are already built into it.
Microprocesser can be control Multiple Application.
eg. System Design.

Microcontroller can be control Single or Particular Application Only.

eg. embedded systems.

Another way of considering this is:

If you want to run a video game you probably need a microprocessor.
If you want to run a microwave oven you probably need a microcontroller.