CORE SKILLS AND KNOWLEDGE
SAFETY
Using equipment that is potentially hazardous is a requirement of this course. Learners will be instructed in the safe use of equipment, including:
- power tools, such as drills, saws, soldering irons, etc...
- chemical etching equipment
- appropriate storage and handling of chemicals including spill management
- toxic substances likely to be encountered including procedures to minimise risk of poisoning
- electrical safety including sources of dangerous voltage or current levels, and what to do in an emergency, e.g. when someone is receiving an electric shock
- workshop safety including safe practices for using equipment, basic first aid and what to do in an emergency
- safety equipment including Residual Current Devices (RCD’s, or safety switches), fuses, circuit breakers, Personal Protective Equipment (PPE).
CORE CIRCUIT CONSTRUCTION SKILLS
Selecting, testing, measuring and calculating is to be incorporated into each module and, at the end of the course, learners will have encompassed:
- breadboarding
- PCB manufacturing
- measurement and calculation of current, voltage, resistance, power, gain, period and frequency, reactance, impedance, inductance, capacitance
- function and operation of select digital circuits
- uses of signal generators, injectors and other waveform sources (e.g. microphones, antennas) types of waveforms, output impedance
- continuity testing
- AC measurement, peak, average and RMS measurements
- circuit loading
- transistor and diode testing
- uses of cathode ray oscilloscopes for measuring and displaying waveforms, triggering, synchronisation, showing phase relationships.
CORE ELECTRONICS KNOWLEDGE (FUNDAMENTALS)
The following knowledge is relevant and basic to most aspects of the course. They are to be encountered and applied frequently:
- safe working practices
- standard symbols, SI units and prefixes
- communication in all forms
- uses of block diagrams
- identification, and orientation of components
- measuring, recording, discussing, researching and reviewing
- electronic systems in homes and industries: what they are, who designs, uses, operates, services and sells them
- uses of computer applications for simulation and drawing circuits and design of printed circuit boards.
In addition the following are to be revised, demonstrated or introduced within the modules as applicable:
- AC and DC sources
- voltage or current control in power supplies
- series, parallel and series/parallel resistive networks
- power dissipation, effects of voltage or current changes, `P = IV`, `P = I^2R`, `P = V^2/R`, power ratings
- magnets, magnetic materials, attraction, repulsion, fields, lines of force
- field around a straight conductor carrying a current, fields around loops and coils carrying a current
- electromagnets, electric motors
- uses of electromagnets in relevant technology
- Faraday’s law
- Lenz’s law.
CONTENT MODULES
Each of the following modules must be covered by the end of the course. Due to the sequential nature of these modules, it is recommended for learners to be proficient with module 1 before attempting the other modules. It is recommended that module 3 on digital circuits be covered before module 4 on microcontrollers.
Module 1: Basic Electricity And Circuits (SUGGESTED 10% OF DELIVERY TIME)
Example experiments and practical projects: Compare voltage and current in a resistor and/or a diode using graphs, create a light activated circuit.
Derived from or related to these projects are topics including:
- voltage, current, resistance and power
- Ohm’s law
- series and parallel circuits
- voltage dividers
- resistors, capacitors, inductors
- resistor colour code and E12 series
- capacitor values and pF code
- continuity
- switches
- semiconductors – diodes, LEDS, transistors
- integrated circuits – voltage regulators (see power supplies), Digital IC’s (see digital) amplifier ICs (see analogue), 555 timer.
Module 2: Analogue Circuits (SUGGESTED 25% OF DELIVERY TIME)
OPERATIONAL AMPLIFIERS
Example practical projects: Light or heat sensing switching circuits, a pre-amplifier for audio applications.
Derived from or related to these projects are topics including:
- IC op-amps and pin-outs
- dual voltage supplies
- inverting and non-inverting amplifiers
- comparators, differential or subtractive amplifiers
- feedback; negative for amplifiers, positive for comparators with hysteresis
- gain as a ratio between input and output voltages, `V_"out" = G xx V_"in"`
- gain of an amplifier in terms of input and feedback resistances, `G = -R_f/R_i`, `G = 1 + R_f/R_i`
- uses of a CRO and multimeter to display or measure input and output levels
- input and output voltage ranges, clipping
- single supply operation
- systems which uses amplifiers.
WAVES
Practical project: build a square wave oscillator, build a tone generator.
Derived from or related to these projects are topics including:
- shapes: square, triangle, sawtooth, sine
- frequency
- wavelength
- astable multivibrator circuits.
FREQUENCY SELECTIVE NETWORKS
Example practical projects: Cross-over network for speakers, high frequency noise rejection in a heartbeat monitor.
Derived from or related to these projects are topics including:
- concept of frequency selective networks
- RC and RL networks, effects of components on frequency spectrum, effects of two component systems on the frequency spectrum
- concept and definition of cut-off frequency, reactance and impedance
- open loop gain, frequency response, bandwidth and its relationship to gain
- concept and definition of bandwidth
- impedance of LCR circuits
- active and passive high pass, low pass, band pass and band stop filters
- LC resonant filters
- decibels (voltage and power).
Module 3: Digital Circuits (SUGGESTED 20% OF DELIVERY TIME)
BASIC DIGITAL CIRCUITS
Example practical projects: a stopwatch, a two digit frequency meter, any counting circuit which involves a clock, counter, decoder and display.
Derived from or related to these projects are topics including:
- difference between digital and analogue signals
- logic gates
- Boolean algebra
- complex gate circuits, truth tables
- flip-flops: SR, D, JK type, and how to configure to a T type
- synchronous and asynchronous circuits
- counters and shift registers
- number bases, octal, binary, hexadecimal compared to decimal, simple addition and subtraction, conversion between bases
- binary code
- decoders demonstrated
- 7-segment display, 5 x 9 display
- simple timing diagrams
- binary coded decimal (BCD) and ASCII code
- simple d/a and a/d converters, e.g. a ladder network of resistors
- multiplexing
- special function IC’s, such as BCD to 7 segment decoder.
Module 4: Microcontrollers (SUGGESTED 7.5% OF DELIVERY TIME)
It is recommended that PICAXE microcontrollers be used:
- they are developed with electronics novices in mind
- they have comprehensive documentation, in language that learners can access
- the programming language is BASIC, and is accessible to learners.
Example practical projects: temperature controlled fan speed controller, LED flashing game.
Derived from or related to these projects are topics including:
- analogue and digital inputs and outputs, voltage and current limitations
- sensors, transducers, and other input/output components
- mechanical switch bouncing, and methods of debouncing
- types and range of sizes of microcontrollers. Manufacturers, performance of different microcontrollers.
Module 5: Power Supplies (SUGGESTED 7.5% OF DELIVERY TIME)
Example practical projects: set or variable voltage power supply, overload protection circuit.
Derived from or related to these projects are topics including:
- AC and DC, rectifiers, transformers
- voltage ripple, smoothing
- voltage regulator IC’s
- circuit protection, Zener clamping, active overload protection, reverse bias protection.
CONSTRUCTION PROJECTS (SUGGESTED 30% OF DELIVERY TIME)
Learners must build their own projects, comprising an original or modified design from concepts covered in the course, appropriately housed and complete with an appropriate level of documentation.
The construction projects will reflect approximately 50 hours total of in-class work including: research; design; building; testing and troubleshooting; and documentation.
Documentation of projects will be formatted and structured in a logical manner and include, as appropriate:
- a rationale or description of the problem that the circuit would provide a solution for
- appropriate reporting and research on options for circuits and components, and on the operation of the selected circuits and components
- the circuit design process, including:
- block diagrams
- any relevant calculations or programs
- tests performs and results of these tests
- schematic diagrams and PCB layout
- an evaluation of the completed circuit
- an operators manual
- a time log of work planned and completed.
The projects will be internally assessed against criteria 1, 2, 3 and 6, as well as any relevant criteria for topic specific projects.
It is suggested that three projects be completed throughout the year; a project containing a digital circuit, a project containing an analogue circuit, and a project of the learners choosing.
Example – Digital Projects:
- PICAXE project involving sensors and displays
- two digit frequency meter
- counting circuit which involves a clock, decoder and display.
Example – Analogue Projects:
- heart rate monitor
- audio amplifier
- crossover network for an audio system.