Electronic Devices

Circuit Board

Electronic devices have circuit boards which is a collection of many circuit parts on a sheet of insulating material. It connects the parts of the circuit to supply electric current and send signals to the parts of the electronic device. The information sent to the device is converted into infrared light through a LED or light emitting diode.

 Many electronic devices use semiconductors which are substances that conduct an electric current better than an insulator does but not as well as a conductor does. The way a semiconductor works depends on how its electrons are arranged.

You can change the conductivity of a semiconductor through doping. It is the addition of an impurity to a semiconductor. Adding the impurity changes the arrangement of electrons.

There are 2 types of doped semiconductors:

*N-Type Semiconductor- when a replaced an atom with another atom results in an "extra" electron

*P-Type Semiconductor- when a replaced an atom with another atom results in a "hole" where an electron could be.

Joining both types of semiconductors results forms a diode. It is an electronic component that allows electric charge to move mainly in one direction. In a diode, where the two layers meet, some “extra” electrons from the n-type layer move to fill the “holes” in the p-type layer. Diodes can also change AC currents to DC by blocking one of the directions of the current.

          Transistors are electronic components that amplify or increase current It can be used in many circuits, including an amplifier and a switch. There are 2 types of transistors:

*NPN transistors- have a p-type layer in between two n-type layers.
*PNP transistors- have an n-type layer in between tow p-type layers.

An entire circuit that has many components on a single semiconductor is called an integrated circuit.

Integrated Circuit

Communication Technology

          Signal is anything, such as a movement, sound, or a set of numbers and letters, that can be used to send information. One signal is sent using another signal called a carrier. Two kinds of signals are: Analog signals, and digital signals. An analog signal is a signal whose properties change without a break or jump between values. Digital signal on the other hand is a signal that represented as a sequence of separate values.

          Radio and TV signals can either be analog or digital. An EM or electromagnetic wave is a wave that consists of changing electric and magnetic fields. They are used as carriers. Radio waves are one kind of EM wave. Radio stations use radio waves to carry signals that represent sound. They travel through the air, and are picked up by a radio antenna. The pictures we see on the screen of out televisions are made b electrons hitting the screen. Audio signals hold the information to make the sound. More and more TVs are going digital; the images and sound of these programs are much clearer than on televisions made for analog broadcasts. A plasma display do not use electron tubes, instead they have thousands of tiny cells with gases. The gases then are charged and it generates colored lights.

Computers

          Computers are electronic devices that perform tasks by following instructions given to it. The information given to the computer is called input while the final result is called an output. The computer processes the information given to it, which is called processing. This could mean adding a list of numbers, making a drawing, or even moving a piece of equipment.

          The first computer was called the ENIAC (Electronic Numeral Integrator and Computer). This computer is much larger than what we use today. The modern computers use microprocessors which are single semiconductor chips that control and execute a microcomputer’s instructions. Computer hardware is the parts or pieces of equipment that make up a computer. These are composed of:

*Input device- gives information, or input to the computer.

*Central processing unit- is the microprocessor; processing on the spot for storage in memory.

*Memory- used to store information.

          *ROM- is the permanent memory such as maintenance, hardware        management, and Start-ups. It cannot be changed or added to.
          *RAM- is the temporary memory. The information is lost when the power is shut off.

*Output device- such as printers, monitors, speakers etc.

Computer Software is a set of instructions or commands that tells a computer what to do. A computer program is software.

There are two kinds of software:

*Operating-system software- handles basic operations needed by the computer
*Application software- tells the computer to run a utility

The internet is a huge computer network made up of millions of computers that can all share information.  Part of the internet is called the WWW or world wide web.