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

How to learn about Electricity and Electronics Everybody plays music from a CD Everybody plays music from a CD We start with binary data We start with binary data We end up with sound coming from a speaker We end up with sound coming from a speaker How does this work? How does this work? Copyright © Texas Education Agency, All rights reserved. 2

Here is what our binary data looks like: Here is what our binary data looks like: Here is what our audio signal looks like: Here is what our audio signal looks like: Copyright © Texas Education Agency, All rights reserved. 3

How do we get from one to another? A series of conversion process steps A series of conversion process steps Sound is created by something that vibrates (moves), which creates pressure changes in the air 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 the pressure to make something move (a coil or diaphram) We can use motion to create or change some amount of electricity We can use motion to create or change some amount of electricity Copyright © Texas Education Agency, All rights reserved. 4

Sound conversion to CD data The value of the voltage depends on the amount of sound (called amplitude) 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 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 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 The binary code is created to be burned on a compact disk Copyright © Texas Education Agency, All rights reserved. 5

CD audio is basically a whole bunch of numbers that record sound levels 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) 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) 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, All rights reserved. 6

Basic Electricity Basic electricity and electronics starts with electrons Basic electricity and electronics starts with electrons Electrons are one of the three fundamental particles Electrons are one of the three fundamental particles All work involves movement All work involves movement Electrons move to create electrical work Electrons move to create electrical work Electronics is the study and use of devices that control the movement of electrons Electronics is the study and use of devices that control the movement of electrons Copyright © Texas Education Agency, All rights reserved. 7

Electrons and Charge How do we make electrons move? How do we make electrons move? Electrons have a charge Electrons have a charge Like charges repel, unlike charges attract Like charges repel, unlike charges attract These forces make electrons move These forces make electrons move F F F Copyright © Texas Education Agency, All rights reserved. 8

Where do we get charge? Charge is a fundamental property of nature Charge is a fundamental property of nature Electrons and protons have a charge Electrons and protons have a charge Electron charge is negative Electron charge is negative Proton charge is positive Proton charge is positive Copyright © Texas Education Agency, All rights reserved. 9

The Atom The fundamental building block of all matter The fundamental building block of all matter Made of protons, neutrons, Made of protons, neutrons, and electrons The type of element is determined by the number of protons in the nucleus The type of element is determined by the number of protons in the nucleus Copyright © Texas Education Agency, All rights reserved. 10

Voltage and Charge Voltage is a measurement of force created by a buildup of 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 Atoms are usually neutral because they have the same number of protons and electrons Charge builds up when electrons are separated from the atom Charge builds up when electrons are separated from the atom This separation takes work in the form of mechanical energy or chemical energy This separation takes work in the form of mechanical energy or chemical energy Copyright © Texas Education Agency, All rights reserved. 11

Voltage and Current Voltage is the force created by a buildup of charge Voltage is the force created by a buildup of charge Also called a potential difference Also called a potential difference Voltage can make electrons move Voltage can make electrons move Electron movement is called current flow Electron movement is called current flow Current flow does the work in an electric circuit Current flow does the work in an electric circuit Copyright © Texas Education Agency, All rights reserved. 12

Common Electrical Units The unit of charge is the COULOMB The unit of charge is the COULOMB Charge has the symbol Q, abbreviation C Charge has the symbol Q, abbreviation C The unit of voltage is the VOLT The unit of voltage is the VOLT The symbol is V, the abbreviation is V The symbol is V, the abbreviation is V The unit of current is the AMP The unit of current is the AMP Current uses the symbol I, abbreviation A Current uses the symbol I, abbreviation A The unit of resistance is the OHM The unit of resistance is the OHM Resistance has the symbol , abbreviation R Resistance has the symbol , abbreviation R Copyright © Texas Education Agency, All rights reserved. 13

Think in Pairs Electricity is two things: Voltage and Current Electricity is two things: Voltage and Current Voltage has two polarities: positive and negative Voltage has two polarities: positive and negative Two types of electrical power: AC and DC Two types of electrical power: AC and DC Electricity has two purposes: as an energy source (power) and as a signal Electricity has two purposes: as an energy source (power) and as a signal Signals can be either analog or digital Signals can be either analog or digital Copyright © Texas Education Agency, All rights reserved. 14

Electricity A good power source A good power source Easy to create Easy to create Easy to control Easy to control Efficient to transmit Efficient to transmit Easy to measure Easy to measure Makes everything work – our way of life depends on it Makes everything work – our way of life depends on it Copyright © Texas Education Agency, All rights reserved. 15

An electric circuit must have a complete path from one side of a power supply (+V) to the other (-V) 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 across a resistor creates current Voltage, current, and resistance follow a rule known as Ohm’s Law Voltage, current, and resistance follow a rule known as Ohm’s Law I = Current equals voltage divided by resistance Current equals voltage divided by resistance VRVR Copyright © Texas Education Agency, All rights reserved. 16

A Simple Circuit All of the voltage is dropped across the resistor All of the voltage is dropped across the resistor Current flows from negative to positive Current flows from negative to positive Ground is defined as zero volts Ground is defined as zero volts Battery Resistor (Load) Current Flow + - Ground Copyright © Texas Education Agency, All rights reserved. 17

Electricity creates an electromagnetic wave also known as a radio signal Electricity creates an electromagnetic wave also known as a radio signal Travels at the speed of light through air Travels at the speed of light through air Travels at nearly the speed of light through a wire Travels at nearly the speed of light through a wire Historically most signals were analog and used AC principles Historically most signals were analog and used AC principles Copyright © Texas Education Agency, All rights reserved. 18

More recent signals are digital and represent coded information More recent signals are digital and represent coded information Digital signals are basically DC voltage switched on and off at a rapid rate Digital signals are basically DC voltage switched on and off at a rapid rate The basic digital switch is a transistor The basic digital switch is a transistor Copyright © Texas Education Agency, All rights reserved. 19

Transistor Basics A semiconductor device A semiconductor device Conductivity is controlled by current Conductivity is controlled by current An example of a voltage controlled device is a MOSFET An example of a voltage controlled device is a MOSFET Made from a silicon crystal Made from a silicon crystal Doped with impurities to allow conductivity to be controlled Doped with impurities to allow conductivity to be controlled Copyright © Texas Education Agency, All rights reserved. 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 Four valence electrons per atom Bonds with four more silicon atoms to create a stable molecule Bonds with four more silicon atoms to create a stable molecule Creates a solid three-dimensional structure Creates a solid three-dimensional structure Si Copyright © Texas Education Agency, All rights reserved.

N-type Doping Adds arsenic, keeps the stable crystal structure Adds arsenic, keeps the stable crystal structure Has an extra electron Has an extra electron Negative charge carrier Negative charge carrier The extra electron becomes free to conduct current The extra electron becomes free to conduct current More arsenic atoms gives more conductivity More arsenic atoms gives more conductivity Si As Si Copyright © Texas Education Agency, All rights reserved.

P-type Doping Gallium has only three electrons Gallium has only three electrons Still keeps the stable crystal structure Still keeps the stable crystal structure Creates a hole where an electron is needed for a bond Creates a hole where an electron is needed for a bond The hole is a positive current carrying particle The hole is a positive current carrying particle Si Ga Si Copyright © Texas Education Agency, All rights reserved.

A Transistor A transistor has 3 layers of semiconductor A transistor has 3 layers of semiconductor NPN or PNP NPN or PNP The regions are called the emitter, base, and collector The regions are called the emitter, base, and collector The key to how it works is that the base is THIN and LIGHTLY DOPED The key to how it works is that the base is THIN and LIGHTLY DOPED N N P Emitter Base Collector Copyright © Texas Education Agency, All rights reserved.

Binary Logic A set of rules that applies to a digital circuit A set of rules that applies to a digital circuit Logic defines the way the circuit will act Logic defines the way the circuit will act Given a set of inputs, the output will produce a specific outcome Given a set of inputs, the output will produce a specific outcome Always acts exactly the same way Always acts exactly the same way We use a truth table to help us define how we want the logic circuit to act We use a truth table to help us define how we want the logic circuit to act Copyright © Texas Education Agency, All rights reserved.

We build the circuit to perform the logic We build the circuit to perform the logic Always does the same thing with the same inputs Always does the same thing with the same inputs We must define each possible input or input combination We must define each possible input or input combination We have to define exactly what output we want for a particular input We have to define exactly what output we want for a particular input Lets look at an example Lets look at an example Copyright © Texas Education Agency, All rights reserved.

Two Bit Binary Adder Adds two binary bits Adds two binary bits Binary can only have two values, 0 and 1 Binary can only have two values, 0 and = 2, which is not valid binary = 2, which is not valid binary Carry 1 Copyright © Texas Education Agency, All rights reserved.

Binary Numbers Binary only has two values, 0 and 1 Binary only has two values, 0 and 1 The decimal number system has ten values, 0 through 9 The decimal number system has ten values, 0 through 9 How do we count higher than 9 in decimal? How do we count higher than 9 in decimal? We add decimal places We add decimal places How do we count higher than one in binary? How do we count higher than one in binary? We add binary bits We add binary bits Computers and electronic devices communicate in binary Computers and electronic devices communicate in binary Copyright © Texas Education Agency, All rights reserved.

MP3 Audio Research Project: Technical details of MP3 audio. Research Project: Technical details of MP3 audio. How does MP3 audio data differ from CD audio data? How does MP3 audio data differ from CD audio data? Copyright © Texas Education Agency, All rights reserved. 29