3. It describes electronic technology that
generates, stores, and processes data in terms
of two states: positive and non-positive.
Positive is expressed or represented by the
number 1 and non-positive by the number 0.
Thus, data transmitted or stored with digital
technology is expressed as a string of 0's and
1's. Each of these state digits is referred to as a
bit (and a string of bits that a computer can
address individually as a group is a byte).
4. • Prior to DIGITAL technology, electronic
transmission was limited
to analog technology, which conveys data as
electronic signals of varying frequency or
amplitude that are added to carrier waves of a
• Broadcast and phone transmission has
conventionally used analog technology.
5. • Digital may refer to:
• Digital data, data that is represented using discrete (discontinuous)
• In technology:
• Digital computer, a computer handling information represented by
• Digital electronics, electronic circuits representing signals by
discrete bands of analog levels, rather than by a continuous range.
• Digital media, media that store digital data.
• Digital signal, a discrete-amplitude signal or bitstream signal
– Digital television, television systems which broadcast using digital
7. • An analog signal can be represented as a series of sine
waves. The term originated because the modulation of
the carrier wave is analogous to the fluctuations of the
human voice or other sound that is being transmitted.
• In telecommunications
an analog signal is one in which a base
carrier's alternating current frequency.
- Broadcast and telephone transmission have
conventionally used analog technology.
8. There are two types of signals that carry
Analog and Digital
9. Analog vs Digital Signals
• The difference between analog and digital signal is that analog is a
continuous electrical signal, whereas digital is a non-continuous electrical
• Analog Signals vary in time, and the variations follow that of the non-
electric signal. When compared to analog signals, digital signals change in
individual steps and consist of pulses or digits.
• Digital signals, similar to Morse code, are sent to a computer which
interprets these into words. A digital signal, a 0 or 1, is sent through the
phone line. For example, when you type the letter A into your computer, it
converts it into 01000001. This 01000001 goes to other computer, which
interprets it as A. A series of eight 0′s and 1′s is called a byte, whereas
each 0 or 1 is called a bit.
10. • The difference between digital and analog signals can also be understood
by observing various examples of different waves, and how they work. In
the 1800′s, analog waveforms were used in conjunction with copper to
relay or transmit conversations.
• The speed at which energy or signals travel down a cable is actually the
speed of the electromagnetic wave, not the movement of electrons.
14. • An electric current is a flow of electric charge. In electric circuits this
charge is often carried by moving electrons in a wire. It can also be carried
by ions in an electrolyte, or by both ions and electrons such as in a plasma.
• Household utility current in most countries is AC with a frequency of
60 hertz (60 complete cycles per second), although in some countries it is
50 Hz. The radio-frequency (RF) current in antennas and transmission lines
is another example of AC.
• Sine waves
• A waveform is a representation of how alternating current (AC) varies with
time. The most familiar AC waveform is the sine wave, which derives its
name from the fact that the current or voltage varies with the sine of the
elapsed time. Other common AC waveforms are the square wave, the
ramp, the saw tooth wave, and the triangular wave. Their general shapes
are shown below.
16. • A static electric charge is created whenever two surfaces contact
and separate, and at least one of the surfaces has a high resistance
to electrical current (and is therefore an electrical insulator). The
effects of static electricity are familiar to most people because
people can feel, hear, and even see the spark as the excess charge is
neutralized when brought close to a large electrical conductor (for
example, a path to ground), or a region with an excess charge of the
opposite polarity (positive or negative)
• When electricity is at rest, it is called static electricity. It refers to
the electric charges that build up on the surface of materials or
substances. These so-called static charges remain until they are
grounded, or discharged.
• Static electricity is generated by friction, or sudden contact – for
instance, rubbing two materials against each other. Ordinarily,
atoms are ‘uncharged’. These are considered neutral substances,
but they can lose or gain electrons through friction.
• Digital circuit
18. • A transistor is a semiconductor device used to amplify
and switch electronic signals and electrical power. It is
composed of semiconductor material with at least
three terminals for connection to an external circuit.
• A voltage or current applied to one pair of the
transistor's terminals changes the current through
another pair of terminals. Because the controlled
(output) power can be higher than the controlling
(input) power, a transistor can amplify a signal. Today,
some transistors are packaged individually, but many
more are found embedded in integrated circuits.
20. • Another name for a chip, an integrated circuit
(IC) is a small electronic device made out of a
semiconductor material. The first integrated
circuit was developed in the 1950s by Jack
Kilby of Texas Instrumentsand Robert Noyce of
21. Difference between Transistor to IC
• An integrated circuit has many components like
resistors,capacitors, transistors .... fabricated in A
transistor has only an NPN or a PNP junction.
Integrated circuits can contain millions of transistors.
They can reduce the size and space requirement of a
circuit. If u have a specific IC then u can reduce the
number of transistors required(in most cases u may
avoid using transistors then).Generally a transistor has
3 or 4 pins.But an IC has a minimum of 8 pins normally.
• .The P and N letters refer to positive and negative
doping in a semiconductor.In PNP transistor (Points iN
Proudly - which also defines the current in Emitter
terminal points inwards in the transistor symbol),
23. Resistors - the most ubiquitous of electronic components. They are a
critical piece in just about every circuit. And they play a major role
in our favorite equation, Ohm’s Law.
Combining the elements of voltage, current, and resistance, Ohm
developed the formula:
V = Voltage in volts
I = Current in amps
R = Resistance in ohms
• The difference between a Transistor and a Resistor is that a
transistor is designed to amplify the electrical current, whereas a
Resistor is designed to reduce the electrical current.
25. • Logic Gate is an elementary building block of a digital
circuit. Most logic gates have two inputs and one output. At
any given moment, every terminal is in one of the two
binary conditions low (0) or high (1), represented by
different voltage levels.
• A LOGIN GATE is an elementary building block of
a digital circuit. Most logic gates have two inputs and one
output. At any given moment, every terminal is in one of
the two binaryconditions low (0) or high (1), represented by
different voltage levels. The logic state of a terminal can,
and generally does, change often, as the circuit processes
data. In most logic gates, the low state is approximately
zero volts (0 V), while the high state is approximately five
volts positive (+5 V).