CfE Physics – SCN 4-09 b & c

1John Ogilvie High School - CfE Physics

CfE Physics – SCN 4-09 b & c

Electronics Input, Process and Output Digital Logic Gates

SCN 4-09b: By contributing to investigations into the properties of a range of electronic components, I can select and use them as input and output devices in practical electronic circuits.

SCN 4-09c:Using my knowledge of electronic components and switching devices, I can help to engineer an electronic system to provide a practical solution to a real-life situation.

2John Ogilvie High School - CfE Physics

CfE Physics SCN 4-09b

Electronics

Input, Process and Output

John Ogilvie High School - CfE Physics

3

Learning Intentions: State that an electronic system consists of

three parts: input, process and output. Identify from a block diagram the input, process

and output subsystems of an electronic system.

Draw a block diagram showing the input, process and output subsystems of an electronic system.


4

Input, Process and Output

Electronic SystemsWhen something is made up of lots of parts which are put together to do a job, it is called a s _ _ _ _ _ .

When the parts are electronic components the system is called an e _ _ _ _ _ _ _ _ _ system.

system.

electronic


5

Electronic Systems

Electronic systems can do lots of jobs.The type of job will depend on the components used to make the s _ _ _ _ _ .A calculator is an example of an electronic system.

Every electronic system has t _ _ _ _ main sections - called sub-systems.These are called the i _ _ _ _ , the p _ _ _ _ _ _ and the o_ _ _ _ _.

system.

three

input, processoutput.


6

Subsystem - Input

Detects some type of e _ _ _ _ _ .(for example: light, heat, sound) and changes it to e _ _ _ _ _ _ _ _ _ energy.This is then passed to the p _ _ _ _ _ _ subsystem

energy.

electricalprocess

What It Does


7

Subsystem - Process

Changes the electrical energy from the i _ _ _ _ so that the system can do its job. This is then passed on to the o _ _ _ _ _ subsystem.

input

What It Does

output


8

Subsystem - Output

Converts the electrical e _ _ _ _ _ from theprocess subsystem into another type of energy which can be used. For example: h _ _ _ , l _ _ _ _ ,m _ _ _ _ _ _ _

energy

heat,movement.

What It Does

light,


9

Block Diagrams

A block diagram is an easy way to draw a system. Instead of drawing a complicated diagram showing all the components, we draw a box or b _ _ _ _ to take the place of the i _ _ _ _ , p _ _ _ _ _ _ and o _ _ _ _ _ subsystems.Each block is labelled so that we k _ _ _ what it is.

blockinput, process output

know


10

Block Diagrams

The block diagram for a calculator is shown above. Any subsystem can be further broken down to smaller and smaller subsystems - down to the actual components if required.

Keypad CalculatingCircuits Display

I nput OutputProcess


11

Block Diagram ExamplesPublic Address System

a lI nput OutputProcess

mmicrophone

amplifier loudspeaker


12

Block Diagram ExamplesSmoke Alarm

Logic Circuits b

I OPSmoke Sensor buzzer

Input Process Output


13

Block Diagram ExamplesIntruder Lamp

Logic Circuits l

I nput OutputProcessHSensor

HeatSensor lamp


14

Learning Intentions State that an input device changes some form of

energy into electrical energy. State that the microphone, thermistor, LDR and

switch are all examples of input device. State that the resistance of a thermistor changes

with temperature. State that the resistance of an LDR decreases

when the light on it gets brighter.


15

Input subsystems contain a device which changes some form of e _ _ _ _ _ into electrical energy.Output subsystems contain a device which changes e _ _ _ _ _ _ _ _ _ e _ _ _ _ _ into some other form.

Input and Output Devices

energy

electrical energy


16

How it Works: The inside of the microphone v_ _ _ _ _ _ _ exactly the same way as the sound waves. This makes identical electrical waves.

Device: microphoneInput Devices

What it looks like:

Circuit Symbol:

vibrates


17

How it Works: The resistance of the thermistor changes as the t_ _ _ _ _ _ _ _ _ _ _ changes.

Device: thermistorInput Devices

temperature

What it looks like:

Circuit Symbol:


18

How it Works: The resistance of the LDR decreases as the light level gets b_ _ _ _ _ _ _ .

Device: Light Dependent ResistorInput Devices

brighter.

What it looks like:

Circuit Symbol:


19

How it Works: Moving the switch from one setting to the other makes or b_ _ _ _ _ the circuit.

Device: switchInput Devices

breaks

What it looks like:

Circuit Symbol:


20

Learning Intentions State that an output device changes electrical

energy into another form of energy. State that a loudspeaker, buzzer, lamp, LED and

electric motors are all forms of output devices. State the energy conversions involved for a

given output device.


21

How it Works: Electrical energy -> Sound energyElectrical waves make vibrations inside the loudspeaker producing sound waves

Device: loudspeakerOutput Devices

What it looks like:

Circuit Symbol:


22

How it Works: Electrical energy -> Sound energyA voltage across the buzzer makes it sound. The buzzer just switches sound on or off.

Device: buzzerOutput Devices

What it looks like:

Circuit Symbol:+


23

How it Works: Electrical energy -> Light energyA voltage across the lamp makes it light. The greater the voltage, the brighter it gets.

Device: lampOutput Devices

What it looks like:

Circuit Symbol:


24

How it Works: Electrical energy -> Light energyA voltage across the LED makes it light. LEDs are used to indicate when something is on or off.

Device: Light emitting diodeOutput Devices

What it looks like:

Circuit Symbol:


25

How it Works: Electrical energy -> Kinetic energy A voltage across the motor makes it turn.The greater the voltage, the faster it turns.

Device: electric motorOutput Devices

What it looks like:

Circuit Symbol: M


26

Learning Intentions Identify from a list an appropriate input device

for a given job. Identify from a list an appropriate output device

for a given job.


27

Examples of input and output applicationsApplication

Output of radio

Input of an automatic lampInput of a heating controller

Output of fan

DeviceLoudspeake

r

L _ _

Thermistor

M _ _ _ _

The output should be s _ _ _ _ _ waves

Reason

The LDR will change resistance when the brightness changes The thermistor will c_ _ _ _ _ resistance when the temperature changes The motor will t_ _ _ the blades of the fan.

LDR

sound

change

turnMotor


28

CfE Physics Electronics

Digital Logic Gates Scn 4-09c:Using my knowledge of electronic components

and switching devices, I can help to engineer an electronic system to provide a practical solution to a real-life situation.


29

Learning Intentions: State that high voltage = logic 1. State that low voltage = logic 0. Draw and identify symbols for 2 input AND and OR gates

and a NOT gate. State that for a NOT gate the output is the opposite of the

input. State that for an AND gate both inputs must be high for

the output to be high. State that for an OR gate either of the inputs must be

high for the output to be high.


30

Digital signals are either on or o _ _ .

An ‘off’ signal has a zero voltage (called ‘l _ _’ ).

An ‘on’ signal has a non-zero voltage(called ‘h _ _ _’ ).

The ‘o _ _’ signal; low state is given the name ‘logic 0’ (most often just ‘0’).

The ‘o _’ signal; high state is given the name ‘logic 1’ (most often just ‘ 1’).

Digital Signalsoff

‘low’

‘high’

‘off’

‘on’


31

High voltage: Logic _

An oscilloscope can show logic states since it measures the high and low voltages.

Digital Signals

1

Low voltage: Logic _

Oscilloscope trace showing a digital logicsignal which is changing from 1 to 0several times.

0


32

Digital logic gates are used to combine or change digital electronic signals. There are three basic types of logic gate called the N _ _ gate (sometimes called an i _ _ _ _ _ _ _ ), the A _ _ gate and the O _ gate.

Logic Gates

NOTinverter AND

OR


33

This is the simplest gate. It has o _ _ input and o _ _ output.The output is always the opposite of the i _ _ _ _ .

The NOT gate

input.

oneone


34

The NOT gate changes the input signal to the opposite state.

Logic Gate

NOT gate (Inverter)

Symbol

How it behaves

NOT Truth table

input output

Input OutputHigh

Low

Low

High(1)

(0)

(0)(1)


35

The AND gate has two inputs and one output. The output of the AND gate is always at logic 0 unless both the inputs are at logic 1 when the output becomes logic 1 as well.

The AND gate


36

The AND gate combines the input signals so that the output is only 1 when both inputs are 1.

Logic Gate

AND gate

Symbol

How it behaves

AND Truth tableInput A Output

High

Low Low

High(1)

(0) (0)

(1)

Input B

Low

Low

High High(0)

(0)

(1) (1)

Low(0)

Low(0)

High(1)

Low(0)

input Aoutput

input B


37

The OR gate has two inputs and one output. The output of the OR gate is always at logic 1 unless both the inputs are at logic 0 when the output becomes logic 0 as well.

The OR gate


38

The OR gate combines the input signals so that the output is 1 when either input is 1.

Logic Gate

OR gate

Symbol

How it behaves

OR Truth tableInput A Output

High

Low Low

High(1)

(0) (0)

(1)

Input B

Low

Low

High High(0)

(0)

(1) (1)

Low(0)

High(1)

High(1)

High(1)

input Aoutput

input B


39

Learning Intentions Explain how to use logic gates for control in

simple situations.


40

1. Donnie's dad wants to be wakened if he gets up at night. Design a system to sound a buzzer if Donnie switches on his light or if he stands on a mat. (A switch is under the mat.)

Logical solutions


41

Solution System Diagram

Light sensor

switchBuzze

r


42

When the light is turned on, the light sensor output is h _ _ _ . This causes the OR gate output to go high which sounds the b _ _ _ _ _ .

high.

How it Works

Light Sensor

Dark Lightlow high

Switch

Open Closedlow high

When the switch under the mat is pressed, it c _ _ _ _ _ _ . This makes its output h _ _ _ .This causes the OR gate output to go h _ _ _ which sounds the buzzer.

buzzer.

closes.high.

high


43

2. A tomato grower wants to protect his delicate plants which are in his greenhouse. Design a warning system to sound a buzzer if it gets too cold during the night (dark).


44


Light sensor

Temperature sensor

Buzzer


45

The buzzer can only switch on when the output from the NOT gate is h _ _ _ .Therefore the output from the OR gate must be l _ _ .

high.

How it Works

The OR gate output can only be low if b _ _ _ the inputs are low. This means it must be both d _ _ _ and c _ _ _ as well.

.

Light Sensor

Dark Lightlow high

Temperature Sensor

Cold Warmlow high

low.

bothdark

cold


46

Grandad can't use the stair light switch easily since he got his walking stick. Design a system which will switch on the stair light automatically when it gets dark. There must be a manual switch as well.


47


Light sensor

Lampswitch


48

When it is dark, the light sensor output is low which is changed to h _ _ _ by the NOT gate. This causes the OR gate output to go high which l _ _ _ _ _ the lamp.

high

How it Works

When the switch is closed, its output is high. This causes the OR gate output to go h _ _ _ which lights the lamp.

.

Light Sensor

Dark Lightlow high

Switch

Open Closedlow high

lights

high


49

4. Design a system for a bathroom to switch on a fan motor when the bathroom gets so steamy, the light from the window is blocked. The fan must only come on when it is hot as well as steamy.


50


Light sensor

MotorTemperatur

e sensor


51

When it is steamy, it gets darker, the light sensor output is l _ _ which is changed to high by the N _ _ gate.When it gets too h _ _ the output from the temperature sensor is h _ _ _ .

low

How it Works

Only when it is hot and steamy at the s _ _ _ time will both inputs of the AND gate be high to make the output high to t _ _ _ the motor.

.

Light Sensor

Dark Lightlow high

Temperature sensor

Cold Warmlow high

NOT

high.hot

same

turn


52

CfE Physics Electronics

End of Unit

CfE Physics – SCN 4-09 b & c

Documents

Transcript of CfE Physics – SCN 4-09 b & c