Beath High School - Int 1 Physics 1

Intermediate 1 Physics

Electronics

Input, Process and Output

Digital Logic Gates

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Intermediate 1 Physics

Electronics

Input, Process and Output

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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

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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, process

output.

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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.

electrical

process

What It Does

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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

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Subsystem - Output

Converts the electrical e _ _ _ _ _ from the

process subsystem into another type of energy

which can be used. For example: h _ _ _ , l _ _ _ _ ,

m _ _ _ _ _ _ _

energy

heat,

movement.

What It Does

light,

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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.

block

input, process output

know

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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

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Block Diagram Examples

Public Address System

a l

I nput OutputProcess

mmicrophon

e

amplifier loudspeak

er

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Block Diagram Examples

Smoke Alarm

Logic Circuits

b

I OP

Smoke Sensor

buzzer

Input Process Output

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Block Diagram Examples

Intruder Lamp

Logic Circuits

l

I nput OutputProcess

HSensor

HeatSensor lamp

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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

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How it Works: The inside of the microphone

v_ _ _ _ _ _ _ exactly the same way as the sound waves. This makes identical electrical waves.

Device: microphone

Input Devices

What it looks like:

Circuit Symbol:

vibrates

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

Device: thermistor

Input Devices

temperature

What it looks like:

Circuit Symbol:

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

Device: Light Dependent Resistor

Input Devices

brighter.

What it looks like:

Circuit Symbol:

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

Device: switch

Input Devices

breaks

What it looks like:

Circuit Symbol:

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How it Works: Electrical energy -> Sound energy

Electrical waves make vibrations inside the loudspeaker producing sound waves

Device: loudspeaker

Output Devices

What it looks like:

Circuit Symbol:

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How it Works: Electrical energy -> Sound energy

A voltage across the buzzer makes it sound. The buzzer just switches sound on or off.

Device: buzzer

Output Devices

What it looks like:

Circuit Symbol:+

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How it Works: Electrical energy -> Light energy

A voltage across the lamp makes it light. The greater the voltage, the brighter it gets.

Device: lamp

Output Devices

What it looks like:

Circuit Symbol:

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How it Works: Electrical energy -> Light energy

A voltage across the LED makes it light. LEDs are used to indicate when something is on or off.

Device: Light emitting diode

Output Devices

What it looks like:

Circuit Symbol:

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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 motor

Output Devices

What it looks like:

Circuit Symbol: M

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Examples of input and output applications

Application

Output of radio

Input of an automatic lamp

Input of a heating controller

Output of fan

Device

Loudspeaker

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

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Intermediate 1 Physics Electronics

Digital Logic Gates

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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’

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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

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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

NOT

inverter AND

OR

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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

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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 Output

High

Low

Low

High

(1)

(0)

(0)(1)

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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

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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 table

Input 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

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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

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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 table

Input 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

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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

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Solution System Diagram

Light sensor

switch

Buzzer

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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 Light

low high

Switch

Open Closed

low 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

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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).

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Solution System Diagram

Light sensor

Temperature sensor

Buzzer

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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 Light

low high

Temperature Sensor

Cold Warm

low high

low.

both

dark

cold

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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.

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Solution System Diagram

Light sensor

Lamp

switch

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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 Light

low high

Switch

Open Closed

low high

lights

high

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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.

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Solution System Diagram

Light sensor

MotorTemperatur

e sensor

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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 Light

low high

Temperature sensor

Cold Warm

low high

NOT

high.

hot

same

turn

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Intermediate 1 Physics Electronics

End of Unit