Transcript ELECTRONIC COMMUNICATION

ELECTRONIC/COMPUTER
AGE
Electronic/Computer Age
 Electronics
– Electrical signals can carry information quickly over wires or
through the air by radio
– Light, Appliances and Entertainment
 Atoms
– An atom is the tiniest part of a material
– There are only 109 elements known to exist
– Compounds --- different kinds of atoms combined together,
e.g. table salt, water etc
– A compound has properties all its own
– Atoms are made of smaller particles with their own properties
– Protons and neutrons in the nucleus and electrons in the orbits
circling the nucleus --- protons and electrons have diff.
charges
Electronic/Computer Age
 Electric Current
– Materials whose atoms give up some electrons easily are
conductors
– Materials that hold tightly to their electrons are insulators
– The flow of electrons is current --- Amperes
– 1 amp = 6 billion billion electrons flowing past a point in 1 sec
– Electromotive force makes a current flow --- Volts
– A battery provides electromotive force
– Resistance is the opposition to a flow of current --- Ohm’s law
– V = IR or I = V/R
Electronic Components & Circuits
– Electronic components or parts control the flow of electricity
--- each component has its own symbol
– Circuits --- different forms in which components are
connected
– Schematics --- drawings that show plans for circuits
– A resistor is used to control the flow of current --- 0.1 – 106 
– Color coded bands indicate the resistance in ohms
– Semiconductors are neither good insulators or good
conductors, e.g silicon
– A diode is made using a semiconductor, it lets current flow in
only one direction
Electronic Components & Circuits
 Transistor
– A resistor that lets a small amount of current control the flow
of a much larger amount of current, e.g. motors, computers
– It is a square wafer a few thousandths of an inch on a side
– A thermistor has a resistance that changes with temperature
– A photoresistor has a resistance that changes with the amount
of light hitting it
 Printed Circuits
– Solder is a method of joining two wires together
– Wires’ contact causes an unintended flow of current --- short
circuit --- use of insulation
– A printed circuit board is a thin board of an insulating material
like fiberglass
– The conducting paths are photographically placed over it
Electronic Components & Circuits
– Once components are mounted on the board, they can be
soldered by an automatic soldering machine
 Integrated Circuits
– It provides a complete circuit on a tiny bit of semiconductor
– They are often less than 1/10th of an inch in length and width
– The drawing of a chip is photographically reduced to form a
mask
– Chips have replaced large bulky circuits and are quite less in
volume and price
– Computers are built using large ICs
 Analog and Digital Circuits
– An analog circuit works with analog signals
– In digital circuits, a voltage above a certain value is coded as a
1 and a voltage below that value is coded as a 0.