8.01-.02 Basic Electricity and Electronics Mr. McClean Concepts of Engineering and Technology Copyright © Texas Education Agency, 2012. All rights reserved

8.01-.02 Basic Electricity and

ElectronicsMr. McCleanConcepts of Engineering

and TechnologyCopyright © Texas Education Agency, 2012. All rights reserved.

How to learn about Electricity and Electronics

Everybody plays music from a CD We start with binary data We end up with sound coming from

a speaker How does this work?

Copyright © Texas Education Agency, 2012. All rights reserved.2

Here is what our binary data looks like:

1001000100110101 1110101000111101

Here is what our audio signal looks like:


How do we get from one to another?

A series of conversion process steps Sound is created by something that

vibrates (moves), which creates pressure changes in the air

We can use the pressure to make something move (a coil or diaphram)

We can use motion to create or change some amount of electricity


Sound conversion to CD data

The value of the voltage depends on the amount of sound (called amplitude)

The voltage value is converted to a number that represents how big or small the voltage is

This number has a binary code that is unique for each voltage value

The binary code is created to be burned on a compact disk


CD audio is basically a whole bunch of numbers that record sound levels

The voltage values are sampled at a fixed rate: 44,100 times per second (Hertz)

We sample and record the sound level whether there is sound or not, resulting in a fixed amount of data per second (1.4 million bits of data per second)Copyright © Texas Education Agency, 2012. All rights reserved.

6

Basic Electricity

Basic electricity and electronics starts with electrons

Electrons are one of the three fundamental particles

All work involves movement Electrons move to create electrical work Electronics is the study and use of

devices that control the movement of electrons


Electrons and Charge How do we make electrons move? Electrons have a charge Like charges repel, unlike charges

attract These forces make electrons move

F

F

F

+ +

+

---


Where do we get charge? Charge is a fundamental property of

nature Electrons and protons have a charge Electron charge is negative Proton charge is positive


The Atom

The fundamental building block of all matter

Made of protons, neutrons,and electrons

The type of element is determined by the number of protons in the nucleus


Voltage and Charge Voltage is a measurement of force

created by a buildup of charge Atoms are usually neutral because

they have the same number of protons and electrons

Charge builds up when electrons are separated from the atom

This separation takes work in the form of mechanical energy or chemical energy


Voltage and Current Voltage is the force created by a

buildup of charge Also called a potential difference Voltage can make electrons move Electron movement is called current

flow Current flow does the work in an

electric circuit


Common Electrical Units

The unit of charge is the COULOMB Charge has the symbol Q, abbreviation C

The unit of voltage is the VOLT The symbol is V, the abbreviation is V

The unit of current is the AMP Current uses the symbol I, abbreviation A

The unit of resistance is the OHM Resistance has the symbol W, abbreviation

R


Think in Pairs Electricity is two things: Voltage and

Current Voltage has two polarities: positive

and negative Two types of electrical power: AC and

DC Electricity has two purposes: as an

energy source (power) and as a signal

Signals can be either analog or digital


Electricity

A good power source Easy to create Easy to control Efficient to transmit Easy to measure Makes everything work – our way of

life depends on it


An electric circuit must have a complete path from one side of a power supply (+V) to the other (-V)

Voltage across a resistor creates current

Voltage, current, and resistance follow a rule known as Ohm’s Law

I =

Current equals voltage divided by resistance

VR


A Simple Circuit

All of the voltage is dropped across the resistor

Current flows from negative to positive Ground is defined as zero volts

Battery

Resistor

(Load)

Current Flow

+

-

Ground


Electricity creates an electromagnetic wave also known as a radio signal

Travels at the speed of light through air

Travels at nearly the speed of light through a wire

Historically most signals were analog and used AC principles


More recent signals are digital and represent coded information

Digital signals are basically DC voltage switched on and off at a rapid rate

The basic digital switch is a transistor


Transistor Basics A semiconductor device Conductivity is controlled by current

An example of a voltage controlled device is a MOSFET Made from a silicon crystal Doped with impurities to allow conductivity to be

controlled

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The metal–oxide–semiconductor field-effect transistor (MOSFET) is a type of transistor used for amplifying or switching electronic signals.

Silicon Crystal Four valence electrons per

atom Bonds with four more silicon

atoms to create a stable molecule

Creates a solid three-dimensional structure

Si

Si Si Si

Si


N-type Doping

Adds arsenic, keeps the stable crystal structure

Has an extra electron Negative charge

carrier The extra electron

becomes free to conduct current

More arsenic atoms gives more conductivity

Si

Si As Si

Si


P-type Doping

Gallium has only three electrons

Still keeps the stable crystal structure

Creates a hole where an electron is needed for a bond

The hole is a positive current carrying particle

Si

Si Ga Si

Si


A Transistor A transistor has 3 layers of semiconductor

NPN or PNP The regions are called the emitter, base,

and collector

The key to how it works is that the base is THIN and LIGHTLY DOPED

NN P

Emitter

Base

Collector


Binary Logic

A set of rules that applies to a digital circuit

Logic defines the way the circuit will act

Given a set of inputs, the output will produce a specific outcome

Always acts exactly the same way We use a truth table to help us define

how we want the logic circuit to actCopyright © Texas Education Agency, 2012. All rights reserved.

We build the circuit to perform the logic

Always does the same thing with the same inputs

We must define each possible input or input combination

We have to define exactly what output we want for a particular input

Lets look at an exampleCopyright © Texas Education Agency, 2012. All rights reserved.

Two Bit Binary Adder Adds two binary bits Binary can only have two

values, 0 and 1

1 + 1 = 2, which is not valid binary

0+ 00

0+ 11

1+ 01

1+ 1

0Carry

1


Binary Numbers Binary only has two values, 0 and 1 The decimal number system has ten

values, 0 through 9 How do we count higher than 9 in decimal? We add decimal places How do we count higher than one in

binary? We add binary bits Computers and electronic devices

communicate in binary


https://www.youtube.com/watch?v=kcTwu6TFZ08



MP3 Audio

Research Project: Technical details of MP3 audio.

How does MP3 audio data differ from CD audio data?


Documents

8.01-.02 Basic Electricity and Electronics Mr. McClean Concepts of Engineering and Technology Copyright © Texas Education Agency, 2012. All rights reserved