Intermediate 1 Physics

1
Intermediate 1 Physics

• Electronics

• Input, Process and Output

• Digital Logic Gates

2
Intermediate 1 Physics

• Electronics

Input, Process and Output
3
Input, Process and Output

• Electronic Systems
• When 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
What It Does

• 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
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Subsystem - Process
What It Does

• 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
output
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Subsystem - Output
What It Does

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

energy
heat,
light,
movement.
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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
output
input,
process
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.

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Block Diagram Examples

• Public Address System

microphone
loudspeaker
amplifier
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Block Diagram Examples

• Smoke Alarm

Output
Input
Process
buzzer
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Block Diagram Examples

• Intruder Lamp

Heat Sensor
lamp
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Input and Output Devices

• 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.

energy
energy
electrical
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Input Devices

• Device microphone

What it looks like
Circuit Symbol
How it Works The inside of the microphone v_ _
_ _ _ _ _ exactly the same way as the sound
waves. This makes identical electrical waves.
vibrates
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Input Devices

• Device thermistor

What it looks like
Circuit Symbol
How it Works The resistance of the thermistor
changes as the t_ _ _ _ _ _ _ _ _ _ _ changes.
temperature
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Input Devices

• Device Light Dependent Resistor

What it looks like
Circuit Symbol
How it Works The resistance of the LDR decreases
as the light level gets b_ _ _ _ _ _ _ .
brighter.
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Input Devices

• Device switch

What it looks like
Circuit Symbol
How it Works Moving the switch from one setting
to the other makes or b_ _ _ _ _ the circuit.
breaks
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Output Devices

• Device loudspeaker

What it looks like
Circuit Symbol
How it Works Electrical energy -gt Sound
energy Electrical waves make vibrations inside
the loudspeaker producing sound waves
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Output Devices

• Device buzzer

What it looks like
Circuit Symbol
How it Works Electrical energy -gt Sound energy A
voltage across the buzzer makes it sound. The
buzzer just switches sound on or off.
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Output Devices

• Device lamp

What it looks like
Circuit Symbol
How it Works Electrical energy -gt Light energy A
voltage across the lamp makes it light. The
greater the voltage, the brighter it gets.
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Output Devices

• Device Light emitting diode

What it looks like
Circuit Symbol
How it Works Electrical energy -gt Light energy A
voltage across the LED makes it light. LEDs are
used to indicate when something is on or off.
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Output Devices

• Device electric motor

What it looks like
Circuit Symbol
How it Works Electrical energy -gt Kinetic energy
A voltage across the motor makes it turn. The
greater the voltage, the faster it turns.
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Examples of input and output applications
Reason

• Application

Device
The output should be s _ _ _ _ _ waves

Output of radio
Loudspeaker
sound
The LDR will change resistance when the
brightness changes
Input of an automatic lamp
L _ _
LDR
Input of a heating controller
The thermistor will c_ _ _ _ _ resistance when
the temperature changes
Thermistor
change
turn
The motor will t_ _ _ the blades of the fan.

M _ _ _ _
Motor
Output of fan
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Intermediate 1 Physics

• Electronics

Digital Logic Gates
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Digital Signals

• 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).
•  

off
low
high
off
on
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Digital Signals

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

1
High voltage Logic _
Oscilloscope trace showing a digital logicsignal
which is changing from 1 to 0several times.
Low voltage Logic _
0
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Logic Gates

• 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.

NOT
inverter
AND
OR
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The NOT gate

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

one
one
input.
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• Logic Gate

NOT gate (Inverter)
Symbol
NOT Truth table
How it behaves
The NOT gate changes the input signal to the
opposite state.
Input
Output
High
Low
(0)
(1)
High
Low
(0)
(1)
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The AND gate
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.
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• Logic Gate

AND gate
AND Truth table
Output
Input B
Input A
Symbol
Low
Low
Low
(0)
(0)
(0)
High
Low
Low
(0)
(0)
(1)
How it behaves
Low
High
Low
The AND gate combines the input signals so that
the output is only 1 when both inputs are 1.
(0)
(0)
(1)
High
High
High
(1)
(1)
(1)
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The OR gate
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.
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• Logic Gate

OR gate
OR Truth table
Output
Input B
Input A
Symbol
Low
Low
Low
(0)
(0)
(0)
High
Low
High
(0)
(1)
(1)
How it behaves
Low
High
High
The OR gate combines the input signals so that
the output is 1 when either input is 1.
(1)
(0)
(1)
High
High
High
(1)
(1)
(1)
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Logical solutions

• 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.)

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Solution System Diagram
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How it Works

• 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.
buzzer.
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.
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
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How it Works

• 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.
low.
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..
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
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How it Works

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

• 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
NOT
hot
high.
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..
same
turn
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Intermediate 1 Physics

• Electronics

End of Unit