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The principles of digital electronics

The circuits and components we have discussed are very useful. You can build a radio or television with them. You can make a telephone. Even if that was all there was to electronics, it would still be very useful. However, the great breakthrough in the last fifty years or so has been in digital electronics. This is the subject which gave us the computer. The computer has revolutionized the way business, engineering and science are done. Small computers programmed to do a specific job (called microprocessors) are now used in almost every electronic machine from cars to washing machines. Computers have also changed the way we communicate. We used to have telegraph or telephone wires passing up and down a country — each one carrying one telephone call or signal. We now have optic fibres each capable of carrying tens of thousands of telephone calls using digital signals.

So, what is a digital signal? Look at [link] . A normal signal, called an analogue signal, carries a smooth wave. At any time, the voltage of the signal could take any value. It could be 2,00 V or 3,53 V or anything else. A digital signal can only take certain voltages. The simplest case is shown in the figure — the voltage takes one of two values. It is either high , or it is low . It never has any other value.

These two special voltages are given symbols. The low voltage level is written 0, while the high voltage level is written as 1. When you send a digital signal, you set the voltage you want (0 or 1), then keep this fixed for a fixed amount of time (for example 0.01 μ s), then you send the next 0 or 1. The digital signal in [link] could be written 01100101.

The difference between normal (analogue) signals and digital signals.

Why are digital signals so good?

  1. Using a computer, any information can be turned into a pattern of 0s and 1s. Pictures, recorded music, text and motion pictures can all be turned into a string of 0s and 1s and transmitted or stored in the same way. The computer receiving the signal at the other end converts it back again. A Compact Disc (CD) for example, can store music or text or pictures, and all can be read using a computer.
  2. The 0 and the 1 look very different. You can immediately tell if a 0 or a 1 is being sent. Even if there is interference, you can still tell whether the sender sent a 0 or a 1. This means that fewer mistakes are made when reading a digital signal. This is why the best music recording technologies, and the most modern cameras, for example, all use digital technology.
  3. Using the 0s and 1s you can count, and do all kinds of mathematics. This will be explained in more detail in the next section.

The simplest digital circuits are called logic gates . Each logic gate makes a decision based on the information it receives. Different logic gates are set up to make the decisions in different ways. Each logic gate will be made of many microscopic transistors connected together within a thin wafer of silicon. This tiny circuit is called an Integrated Circuit or I.C. - all the parts are in one place (integrated) on the silicon wafer.

Questions & Answers

what is definition of hydrocarbon
jessha Reply
it is the atoms that Contain of C atoms and H atoms only
Xolani
You mean molecules
Jc
yea 💯
Xolani
want to ask about Rays,,,,i want to know about angle symbols
Freddy Reply
what is free fall
Tshepo Reply
A free falling object is an object that is falling under the sole influence of gravity
Thabiso
what is non conservative force
Karabo
force for which work done in moving an object between two points is independent of the path taken
Londiwe
non conservative forces: are forces whose work done depend on the pathe of an object for example.... the friction depend on the path you took samething with applied force depend on the path you took....but conservative forces such as gravitational force does not depend on the path of an object since
MINENHLE
since it always there... no matter where you at in the field of gravity but the gravitational force is always there hence is doesnt depend on the path
MINENHLE
which i could show you mathematically but i cant send pictures
MINENHLE
wish i mean
MINENHLE
what is oxidizing agent in terms of electons
Yonela Reply
how to calculate a speed in terms of energy principle
Buntle Reply
Wnet=change in kinetic energy
Bukani
Heyy. Why is electroplating important?
Sofia Reply
it prevent metals from rust
Thabang
Thank you
Sofia
improve the surface qualities of objects—such as resistance to abrasion and corrosion, lubricity, reflectivity, electrical conductivity, or appearance
MINENHLE
state work energy theorem in words
thamisanqa
chatelie'rs principle
Kabelo Reply
Le Chartelier's Principle states that when an equilibrium in a closed system is disturbed,the system will re-instate the new equilibrium by favouring the reaction that will oppose the disturbance
Asavuma
that's my classmate 🤘👍😊
Mihlali
Mihlal Zungu 👌👌👌
Zwelenkosi
ewe khetho
Mihlali
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Zwelenkosi
what is a Reaction Rate
Athandile Reply
Is the change in concentration of reactants or products per unit time
Siphamandla
thanks
Athandile
how will the increase in number of moles affect the reaction
Lonwabo Reply
The increase in number of moles is the same as the increase in concentration. The increase in concentration will result the increase of the rate of the reaction due to more number of moles in that particular vessel. The increase in number of moles = faster the reaction rate
Siphamandla
How do we state the collision theory?
Yiseka Reply
collision theory tells us of how reaction occur and how it is differ in different reactions now u look on how temperature affect reaction, if higher temperature it means the higher the kinetic energy and particles will therefore start to move around much more actively or faster .now the collision w
Lonwabo
now collision will occur
Lonwabo
what factors affect collision theory
Yolisa
Temperature Concentration pressure
Ziyanda
The phenomenon that describes the change in the frequency
Neo Reply
Doppler effect
sinelizwi
is the apparent /percieved change in the frequency of a sound eeither a source or a listener is moving relative to each other
thamisanqa
how is doppler effect detected?
Mellis
like ripple effects of frequency
TYREN
soind wave light detectors
TYREN
sound
TYREN
away is low incoming approaching in loud
TYREN
what formula we use to work out the light
TYREN
does the rate of reaction calculated by reactant equal to product
mudodzwa Reply
formula of heat reaction
Anelisiwe Reply
final energy-initial energy of substances
Chantel
what is the difference between ethene and ethane
Joy Reply
Ethane is a saturated organic molecule while ethene is unsaturated Ethane has 2 carbon atoms and 6 hydrogen atoms, while ethene has 2 Carbons and 4 hydrogens Ethane has single bond between the 2 Carbon atoms while ethene has double bond
Rito
How do you know that the reaction is in acid medium or basic medium
Miss Reply

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Source:  OpenStax, Siyavula textbooks: grade 12 physical science. OpenStax CNX. Aug 03, 2011 Download for free at http://cnx.org/content/col11244/1.2
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