what are Infrared LEDs ?

Infrared LEDs are just like ordinary LEDs but the light output cannot be seen. To view an infrared LEDs, turn it on with the appropriate battery and dropper resistor and view it with a camera. You will see the illumination on the screen. Infrared LEDs are sometimes clear and sometimes black. They operate just like a red LED with the same characteristic voltage-drop of about 1.7v. Sometimes an infrared LED is pulsed with a high current for a very...

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Integrated Circuit chips

Figure below shows what is often referred to as an integrated circuit (IC). The circuit is actually etched onto a tiny wafer or “chip” of silicon, embedded in a black plastic body, which is properly referred to as the “package.” Tiny wires inside the package link the circuit with the two rows of pins on either side.                                       ...

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Sound , Electricity & Sound

Time to establish a clear idea of how sound is transformed into electricity and back into sound again. Suppose someone bangs a gong with a stick. The flat metal face of the gong vibrates in and out, creating sound waves. A sound wave is a peak of higher air pressure, followed by a trough of lower air pressure. The wavelength of the sound is the distance (usually ranging from meters to millimeters) between one peak of pressure and the next peak. The...

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origin of LoudSpeakers

Loudspeakers utilize the fact that if you run a varying electrical current through a coil situated in a magnetic field, the coil will move in response to the current. This idea was introduced in 1874 by Ernst Siemens, a prolific German inventor. (He also built the world’s first electrically powered elevator in 1880.) Today, Siemens AG is one of the largest electronics companies in the world. When Alexander Graham Bell patented the telephone in...

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Best Android apps for Electronic and Electrical Engineers

1.Electrodroid ElectroDroid is a simple and powerful collection of electronics tools and references.                             Download Electrodroid free 2.Everycircuit EveryCircuit is not just an eye candy. Under the hood it packs custom-built simulation engine optimized for interactive mobile use, serious numerical methods, and realistic device models. In short, Ohm's...

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what is a Relay ?

A Relay is an electromagnetic device which is used to isolate two circuits electrically and connects them magnetically. It is basically used in intrerfacing electronic circuit to an electric circuit. it means that a small DC voltage drives circuits working at large voltages like 230V AC (as in our homes). A Relay consist of two parts 1. Input 2. Output Input consist of a coil which gets energized when a voltage with appropriate magnitude is applied...

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Soldering on a perfboard

Carefully note the position of a component on your bread- board, and then move it to the same relative position on the perfboard, poking its wires through the little holes. Turn the perfboard upside down, make sure that it’s stable, and examine the hole where the wire is poking through, as shown in Figure below.  A copper trace surrounds this hole and links it with others. Your task is to melt solder so that it sticks to the copper and also...

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All about Diodes

A diode is a very early type of semiconductor. It allows electricity to flow in one direction, but blocks it in the opposite direction. (A light-emitting diode is a much more recent invention.) Like an LED, a diode can be damaged by revers- ing the voltage and applying excessive power, but most diodes generally have a much greater tolerance for this than LEDs. The end of the diode that blocks positive voltage is always marked, usually with a circular...

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What are capacitors?

DC current does not flow through a capacitor, but voltage can accumulate very quickly inside it, and remains after the power supply is disconnected. Figures below may help to give you an idea of what happens inside a capacitor when it is fully charged. In most modern electrolytic capacitors, the plates have been reduced to two strips of very thin, flexible, metallic film, often wrapped around each other, separated by an equally thin insulator....

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All about Switches

When you flip a toggle switch  it connects the center terminal with one of the outer terminals. Flip the switch back, and it connects the center terminal with the other outer terminal, as shown in Figure below:  The center terminal is called the pole of the switch. Because you can flip, or throw, this switch to make two possible connections, it is called a double-throw switch.  Some switches are on/off, meaning that if you throw...

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Exploring Potentiometers

Potentiometers come in various shapes and sizes, but they all do the same thing: they allow you to vary voltage and current by varying resistance. Most potentiometers are held together with little metal tabs. You should be able to grab hold of the tabs with your wire cutters or pliers, and bend them up and outward. If you do this, the potentiometer should open up as shown Depending whether you have a really cheap potentiometer or a slightly...

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How much voltage does a wire consume?

 Normally, we can ignore the resistance in electric wires, such as the little leads of wire that stick out of resistors, because it’s trivial. However, if you try to force large amounts of current through long lengths of thin wire, the resistance of the wire can become important. How important? we can use Ohm’s Law to find out. Suppose that a very long piece of wire has a resistance of 0.2Ω. And we want to run 15 amps through it. How much...

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How an LDR(light dependent resistor) works!!!!

An LDR is a component that has a resistance that changes with the light intensity that falls upon it. They have a resistance that falls with an increase in the light intensity falling upon the device.    An LDR is made of a high resistance semiconductor. In the dark, an LDR can have a resistance as high as a few megaohms (MΩ), while in the light, an LDR can have a resistance as low as a few hundred ohms. If incident light on an...

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Know about Resistor color code!!

RESISTOR COLOR CODE Some resistors have their value clearly stated on them in microscopic print that you can read with a magnifying glass. Most, however, are color-coded with stripes. The code works like this: first, ignore the color of the body of the resis- tor. Second, look for a silver or gold stripe. If you find it, turn the resistor so that the stripe is on the righthand side. Silver means that the value of the resistor is accurate within...

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