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e-learning in
Electronics
The Design Process
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Lesson 1: Circuit Simulations
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Lesson 2: Design Decisions
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Crocodile clips + modular circuit design
Lesson 4: Building the Prototype
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Modular circuit design
Lesson 3: Realising my Design
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Crocodile clips
Breadboarding
Lesson 5: Manufacture
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PCB design / Automatic manufacture
Lesson 1
Circuit Simulations
Crocodile clips
Objectives
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Aim
 Develop a students electronics design skills though e-learning.
 Develop confidence and knowledge in the use of crocodile
clips.
Objectives
 Construct simple circuits using crocodile clips.
 Make informed decisions over the choice of switches used in
electronics circuits through practical experience of their operation.
 Incorporate logic gates as a means of controlling decisions within
basic circuits.
 Discover ways of monitoring circuit action using probes, on screen
messages and graphical images.
 Investigate the action of Astable and Monostable clocks using the
prepared circuits in the package.
1. Navigation and Tutorial
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HTML link to crocodile
clips
The Crocodile Tutorial
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The 2 tutorials under Help provides an
effective route for investigating the
initial workings of crocodile physics.
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Activity 1
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Follow the Electronics tutorial. This will
provide you with the initial skills
required to investigate this package.
2. Switching
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In order to provide a clean transition
from 0 to 1 in TTL logic circuits
switches should be pulled cleanly
between 0V and 5V. This is done using
a pull down resistor R of 470Ω
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Activity 2 – Using JU1_switches
Set the circuit with a logic monitor on
the output, then investigate the action.
Extension:
The circuit you have made is
commonly known as a Pull Up switch.
Try designing a pull down switch.
Sketch solution opposite:-
3. Logic Gates
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Activity 3: Investigate the operation of the AND gate using the components provided in JU1_And,
then replace the AND gate with the OR gate provided. Now try completing the truth table for the
OR gate below.
4. Output Displays – The LED array
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An LED normally needs a forward
voltage drop of 2V and sufficient light
is emitted with 10mA. A resistor is
usually added to protect the LED from
damage.
Activity 4: Find the value of the
resistor needed to control the current
at 10mA when the supply voltage is
5V. (Use JU1_LED)
Extension:

Add an Ammeter in series with the
LED, Resistor and find the safe current
which turns on the LED.
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Fill in Answer here =
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Now retry this with a voltage of 9V as
shown opposite. What protective
resistor is needed in this case?
JU1_switches_NOT
JU1_And_gates
JU1_LEDs
5. Monostable v Astable Clocks
Monostable.
 A trigger pulse produces a
single pulse of fixed duration.
Astable
 This is a free running and
produces a continuous supply of
pulses at the output.
Creating my First Clock
Activity 5: Using the models – Examples – Electronics Examples – Oscillator 1
provided investigate the settings required to produce an Astable clock with a
frequency of 1Hz or period of 1s. You will need to alter the resistor that
starts as 22k. Use the pulse in the graph to monitor the output frequency.