electrical engineering full day

8/18/2019 Electrical Engineering Full Day

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11

Electricity andCircuits

Developed by Dr. Rhett Davis

(NCSU) and Shodor


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22

What Do Engineers Do?

• Study the forces of nature• Apply them to do useful thin s

• !"ample#$ater $heel %$hat are the forces& %'o is it useful&


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Water Wheels

• $ater heels are *echanical !n ineerin

• +oday, e-ll loo at !lectrical !n ineerin

+ =


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What do you need

to make a Water Wheel Work?• $ater % *a es everythin or

• River % Source of flo in ater • /ipes % +o direct the ater here you

ant it to o and re ulate the flo

• $heel % +o convert the force of theflo in ater into force to rind the

heat


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What’s a similar Electrical

Engineering Problem?

• +urn on a li ht %$ater 0 !lectricity %River 0 1attery %/ipes 0 Resistors, $ires %$heel 0 2i ht 1ulb


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What do you need

to make a Light Bulb Work?• !lectricity % *a es everythin or

• 1attery % Source of flo in !lectricity• Resistors, $ires % +o direct the

electricity here you ant it to o and

re ulate the flo• 2i ht 1ulb % +o convert the force of the

flo in electricity into li ht


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Terminology

• Electric Potential % li e the hei ht of the ater % Symbol (3) % Units (3olts 3)

• Current % li e the number of allons of ater that floevery second % Symbol (4) % Units (Amperes % A)

• Power % li e the amount of heat that can be roundeach second, or bri htness of li ht % Symbol (/) % Units ($atts % $) % N5+!# /6473


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88

Battery

• Source of constant potential (8 3)• 9 lead (red ire) % outflo from hi h potential

• lead (blac ire) % inflo to lo potential


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99

Light Emitting Diode !LED"

• !mits li ht hen currentflo s throu h it

• Current can only flo inone direction, from 9 to (li e a ater heel that

on-t o in reverse) % 2on lead (9) % Short lead ( )


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1010

#esistor

• Ne term# % Resistance % ho easy is it for

current to flo

% Symbol (R) % Unit (5hm % :) % N5+!# 3647R

• Ne circuit element % Resistor % Re ulates the flo of current % 2i e a pipe for electric current to flo % Resistance ;


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1111

Breadboard

• 1readboards areused to connect

thin s >uic ly

• ?ou can proto typecircuits >uic ly


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1212

E$ercise

• Use the battery, thebreadboard, the resistor,

and the 2!D to ma ethe 2!D turn on.• @ollo the 2!D CircuitB

in your handout.• $hy is the resistor

necessary&


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1313

Ca%acitor

• 2i e a lass that holds ater % +op of lass (9) lon lead (no stripe), should al ays be at hi h

potential % 1ottom of lass ( ) short lead ( ith stripe), should al ays be at

lo potential

• +he more electricity flo s in, the hi her the volta e( ater level)

• A lar e capacitor is li e a ide lass % Needs more ater (electricity) to et to the same hei ht (volta e)


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1414

&&& Timer Chi%

• Used to oscillate bet een a hi h (3cc) and lo( ND) volta es

• Stays hi h until +hreshold rises above =E 3cc, then

s itches lo and lets current flo in throu hDischar e pin• Stays lo until +ri er falls belo


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1515

E$ercise

• o to http#==falstad.com=circuit=• Choose Circuits 0 FFF +imer Chip 0 S>uare

$ave enerator • 1uild the circuit sho n• Use the output to po er the 2!D Circuit from

first e"ercise

• FFF +imer CircuitB in your handout ives thecircuit, for convenience• Guestion# $hich capacitor ma es the 2!D

blin faster& $hy&

http://falstad.com/circuit/http://falstad.com/circuit/


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1616

&&& Timer Circuit

• +ips# % @ollo the rou h

layout sho n hereon your breadboard

% Use the blac ireand left rails for

round

% Use the red ireand ri ht rails forthe 83 battery 9lead


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1717

Digital Circuits

• Analo Circuits % $hat e-ve seen up to no

% can have any volta e(in our case, anythin bet een H3 and 83)

% Useful for interfacin to the real orldB

• Di ital Circuits % can have only t o volta es# hi h I lo

(in our case, only H3 and F3) % Useful for processin information reliably


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1818

Transistors

• 1asically a s itch• + o types that e ill loo at

% N*5S % closed hen input is hi h % /*5S % closed hen input is lo

• !"ercise % o to http#==falstad.com=circuit % Choose Circuits 0 2o ic @amilies

0 C*5S 0 C*5S 4nverter % Clic to to le input. $hat

happens to the output&


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1919

Logic 'ates

• Can be used to build upcomple" functions

• !"ercise % o to

http#==falstad.com=circuit % Choose Circuits 0 2o ic

@amilies 0 C*5S 0

C*5S NAND % Clic to to le inputs.$hat happens to theoutput&


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2020

(li% (lo%s

• Used to implement memoryB in a circuit• Allo s behavior to chan e over time• !"ercise

% o to http#==falstad.com=circuit %Choose Circuits 0 Se>uential 2o ic 0

@lip @lops 0 *aster Slave @lip @lop %Clic to to le input DB. $hen does theoutput GB chan e&


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2121

Counters

• Counts up from Jero to a certain number andstarts over

• 1inary arithmetic is used• An e"ample of a more comple" di ital circuit• !"ercise

% o to http#==falstad.com=circuit % Choose Circuits 0 Se>uential 2o ic 0 Counters 0 K

bit Ripple Counter % $atch the output chan e. $hat is the hi hest count

value& % $hat is the input C2LB& $hat does it remind you of&


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2222

)* , Counter Chi%

• Combines all that ehave discussed intoone easy to usepac a e

• Refer to the MK8ECounter Circuit in your

handout


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2323

The -eed .or /oltage #egulators

• *ost Di ital 2o ic runs on F3 or less• +he MK8E Counter Chip on-t or ith

our 83 battery• +o ma e it or , e need to re ulateB

the volta e from 83 to F3


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0ener Diode

• Current flo in from9 to is clamped at

H.O 3• Current flo in from

to 9 is clamped atF.< 3

% lead =o stripe (9) % lead ith stripe ( )


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2525

/oltage #egulator Circuit

Note5ppositedirectionfrom the 2!D


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2626

E$ercise

• o to http#==falstad.com=circuit• Choose Circuits 0 Diodes 0 Pener Diodes 0

3olta e Reference

• Ri ht clic on volta e source 0 !dit 0DC 5ffset 6 83• Ri ht clic on QHH : resistor 0 !dit 0

resistance 6 FH :• Ri ht clic on Jener diode 0 !dit 0

Pener volta e 6 F.< 3• $hat is the lo est value of resistance for the

second resistor that eeps the volta e at F3&$hat does this mean&


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Putting it all together

• +ips % @ollo the rou h

layout sho n here onyour bread board

% Use the blac ire andleft rails for round

% Use the red ire andone ri ht rail for the 83battery 9 lead

% Use the oran e ireand the other ri ht railfor the F.

electrical engineering full day

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