Transcript Pupil Activity

Gary Plimer 2005
Modular Electronics

Use the systems approach.

Enables a structured approach to problem
solving.

Systems diagrams are used to provide a circuit
overview.

All electronic circuits have an input, a process
and an output

Identifying these basic parts is the first step
towards a solution
Gary Plimer 2005
E&L Modular System Boards
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TP
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OR GATE
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THIS IS A
CHIP BUTTY
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Although the CDT department has modular boards and
you will get the opportunity to use these, it is much
easier to use simulation software. Therefore, for the
majority of activities, you will simulate rather than build
boards.
Gary Plimer 2005
Analogue System Boards
An analogue signal varies according to the physical
surroundings. For example, the E&L light-sensing unit will
send out a voltage that is proportional to the amount of
light falling on the LDR.
TP
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Control Studio (Alpha) Boards
Gary Plimer 2005
Analogue Input Transducers
Typical analogue input transducers are:
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input voltage units
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light-sensing units
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temperate-sensing units
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moisture/rain sensor units
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sound-sensing units.
Gary Plimer 2005
Digital Input Transducers
A digital signal is one which has only two settings, on or
off. In electronic terms it has only two levels, high or low.
O/P
IND
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TP
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ACTIVE
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Gary Plimer 2005
Digital Transducers
Typical digital input transducers
are:
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switch units
magnetic switch units
pulse generator units.
Logic on or high is Logic 1
off or low is Logic 0.
Gary Plimer 2005
Output Transducers
Output transducers take an electrical signal and change it
into a physical output. They include the output boards in
modular systems or output components in any electronic
system.
Gary Plimer 2005
Pupil Activity – Light Sensing
1) Draw a block diagram of the system
2) Draw a Systems diagram showing Input Process and
Output stages
3) Construct the circuit on Control Studio
4) In your own words, explain what is happening
Gary Plimer 2005
Pupil Activity – Light Sensing
1) Draw a block diagram of the system
2) Draw a Systems diagram showing Input Process and Output stages
3) Construct the circuit on Control Studio
4) In your own words, explain what is happening
5) What does the inverter do?
Gary Plimer 2005
The Inverter OR NOT Gate
NOT Gate Symbol
Input
Signal
0
Output
Signal
1
1
0
Truth Table
Gary Plimer 2005
Pupil Activity
1) Draw a block diagram of the system
2) Draw a Systems diagram showing Input Process and
Output stages
3) Select suitable boards and construct the circuit in Control
Studio
4) In your own words, explain what is happening
Gary Plimer 2005
Pupil Asignment
A gardener needs a system which will detect when the soil in
his garden requires watering. Design a system which will
warn the gardener when he should water his plants.
1) Draw a block diagram for the new system.
2) Draw a system diagram.
3) Select suitable boards and construct your circuit in
Control Studio.
4) Name each of the boards used.
5) Describe the operation of the circuit.
Gary Plimer 2005
Possible solution
Gary Plimer 2005
Pupil Assignment
Government legislation states that food should be stored below 18 C.
Design an electronic system that will warn the freezer user if the
temperature rises above this preset level.
For the purposes of the simulation, the
alarm should sound if the temperature rises
above normal room temperature.
The alarm should alert the user even if they
are not in the same room as the freezer.
1)
2)
3)
4)
5)
Draw a system diagram to represent a suitable system.
Draw a block diagram of a possible solution to the problem.
Identify all sub-systems.
Test your solution using modular boards.
Explain how your system works.
Gary Plimer 2005
Pupil Activity
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O/P
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RANGE
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ACTIVE
HIGH
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An E&L system is shown above,
1)
2)
3)
4)
5)
6)
7)
Draw a system diagram for the above system.
Draw a block diagram of the system shown.
Connect the sub-systems as shown.
Make the power connection.
Test out the operation of the system by pressing the switch.
Explain what would happen if an inverter was added.
State where the inverter would be positioned.
Gary Plimer 2005
AND Control
1)
2)
3)
4)
5)
6)
7)
Draw a system diagram for the system above.
Draw a block diagram of the system shown.
Connect the sub-systems as shown using Control Studio.
Press switch A only.
Press switch B only.
Press both switches at the same time.
Explain how the AND gate works.
Gary Plimer 2005
AND Gate
Input A Input B Output
0
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Truth Table
And Gate Symbol
Gary Plimer 2005
OR Control
1)
2)
3)
4)
5)
6)
7)
Draw a system diagram for the system above.
Draw a block diagram of the system shown.
Connect the sub-systems as shown using Control Studio.
Press switch A only.
Press switch B only.
Press both switches at the same time.
Explain how the OR gate works.
Gary Plimer 2005
OR Gate
Input A Input B Output
0
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1
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OR Gate Truth Table
OR Gate Symbol
Gary Plimer 2005
Pupil Assignment
A washing machine manufacturer decides that to
improve efficiency the washing machine should not
start until two conditions have been met.
The motor in the washing machine should only
operate if:
a) The water is at the correct temperature.
b) The water is at the correct level.
1) Draw a system diagram to represent a suitable
system.
2) Draw a block diagram of a possible solution to
the problem.
3) Identify all sub-systems.
4) Test your solution using modular boards or
Control Studio.
5) Explain how your system works.
Gary Plimer 2005
Solution
Gary Plimer 2005
Pupil Assignment
Automatic doors should open from both inside and out. Design a
simulation to solve this problem.
For this simulation a combination of light sensors and switches can be
used.
A light sensor should be used to open the doors from the outside.
A switch should be used to open the doors from the inside.
A solenoid unit should be used to simulate the door mechanism.
1)
2)
3)
4)
5)
Draw a system diagram to represent a suitable system.
Draw a block diagram of a possible solution to the problem.
Identify all sub-systems.
Test your solution using modular boards.
Explain how your system works.
Gary Plimer 2005
Solution
Gary Plimer 2005
Pupil Activity (E&L)
Draw a system and block diagram for the system shown.
Turn the potentiometer dial on the pulse generator fully clockwise.
Record the output from the system.
Turn the potentiometer dial on the pulse generator fully
anticlockwise. Record the output from the system.
Explain in your own words what the pulse generator does.
Is the pulse generator:
 an input transducer?
 an output transducer?
 a signal-processing device?
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Gary Plimer 2005
Pupil Activity
Using Control Studio,
Copy the block diagram below
Build the modular board system
Describe in your own words what is happening
Push
Switch
Power
Connec tion
Pulse
Generator
And Gate
Transd uc er
d river
Bulb
Unit
Gary Plimer 2005
Latch Unit
Using E&L or Control Studio
Draw a block diagram for the system shown
Build and test the system
Describe in your own words what the latch unit does
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INPUT
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HIGH = ON
LOW = OFF
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TC4011BP
864BHB
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LATCH
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864BHB
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Gary Plimer 2005
Latch Unit
INPUT
IND
OUTPUT
IND
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LATCH
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TC4011BP
864BHB
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A latched system is one that remains on until it is reset. It is often called a
memory system as it ‘remembers’ that the switch has been pressed until
the reset on the latch is pressed.
Note: the inverter is needed because the latch unit only works as the
voltage signal is dropping (E&L) – this is called negative-edge
triggering. The inverter allows the system to work when the voltage
signal is rising, as happens with a normal switch unit. This converts the
overall system to positive-edge triggering.
Gary Plimer 2005
Pupil Assignment
Your Technological Studies room
has an infrared burglar alarm
system fitted. The trouble is that it
sounds each time someone walks
into the room. Redesign the system
so that it works in a more
acceptable fashion
For the purpose of this simulation the alarm should sound if a light
beam is broken.
There should be a master switch in the janitor’s office.
The alarm should not sound when the system is not ‘set’.
Once set, the alarm should sound if the light beam is broken.
The alarm should continue to sound even if the burglar leaves the
room.
The janitor should be able to reset the system when the police
arrive.
Gary Plimer 2005
Relay – Pupil Activity
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Draw a system diagram for the system shown below.
Draw a block diagram of the system.
Connect the sub-systems as shown.
Press the switch unit and record what happens at the output.
Gary Plimer 2005
Relay Operation
SOFT IRON
ARMATURE
PIVOT
The ‘clicking’ sound at the output is
caused by the contacts of a switch
inside the relay closing. The contacts
are moved by the electromagnet
energising.
A point that must be understood is
that when the relay contacts close,
it provides no power to the
external circuit. To drive anything
from a relay, a separate power
supply must be provided.
SOFT IRON
CORE
COIL
SPRING
TERMINALS
CONTACT
TERMINALS
COIL
TERMINALS
A relay is used to power a large
current/voltage device from a
low current/voltage control
circuit.
Gary Plimer 2005
Pupil Activity
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Draw a block diagram of the system shown below.
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Using E&L, build and test the following system.
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In your own words describe what a relay is used for.
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ACTIVE
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Gary Plimer 2005
Pupil Activity
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Draw a block diagram of
system shown
the
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Using Control Studio build the
circuit
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Complete the truth table
on the next slide
shown
Gary Plimer 2005
Pupil Activity Continued
Magnetic switch
Light sensor
Push switch
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Bulb
Gary Plimer 2005
Input/Output Unit
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TP
Draw block diagrams of
both systems
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This unit is used to
connect external
devices
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O
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Gary Plimer 2005
Pupil Activity
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Draw a block diagram of the system.
Connect the sub-systems as shown.
Adjust the potentiometer dial to the mid-position.
Press the switch and hold. Note what happens.
Try the same with the dial at different positions.
Record the actual time delay for each position.
Position
Fully clockwise
Mid-position
Full anti-clockwise
Delay
Gary Plimer 2005
Comparator

Draw a block diagram of
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Using Control Studio build the circuit

Try adjusting the comparator dial and observe what happens
The comparator compares a
reference voltage to an input
voltage. If the input voltage is
greater than the reference voltage
the comparator gives a high signal
out, (switches on buzzer).
COMPARATOR
the system
Gary Plimer 2005
NAND & NOR Boards
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SB
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NAND GATE
In ve rte r
An d G a te
E & L INSTRUMENTS Ltd
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NOR GATE
In ve rte r
NOR
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O r G a te