GCSE Electronics revision AQA

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Electronics revision Nicholas wills and Ross
Materials, Processes and Practices
Properties of Plastics: Electrical insulator, Thermal insulator, Weather resistant, Chemical
resistant, Corrosion resistant, heat resistant, many colours available, easily shaped and formed, easily
injected blown and formed, easily fabricated. Self Lubricating, Impact Resistant.
Thermoplastics can be heated and shaped many times. Types of Thermoplastic include acrylic,
high impact polystyrene (HIPS), ABS, PVC, Nylon
Thermosetting plastics can only be heated and shaped once. Types of these plastic include glass
reinforced plastic and epoxy resin.
Soft Woods e.g. Pine. Hardwood e.g. Oak, Mahogany, Beach. Manufactured boards e.g. Plywood
and MDF.
Grain Patterns ­ Growth rings visible on the surface
Colour ­ Different tree species vary greatly in colour.
Texture ­ Different tree species have different surfaces and cell structures
Workability ­ Some varieties are much easier to work with than others
Structural Strength ­ Different Species vary from strong to weak.
Main properties of metals:
Elasticity ­ The ability to regain its original shape after its been deformed.
Ductility ­ The ability to be stretched without breaking
Malleability ­ The ability to be easily pressed and hammered into shape
Hardness ­ Resistance to scratches cutting and wear
Brittleness ­ How likely it is to break without bending
Tensile Strength ­ The ability to retain strength when stretched
Toughness ­ Resistance to breaking bending or deforming
Non-ferrous metals contain no iron and are non-magnetic. E.g. Aluminium, Copper, brass, Duralium
Ferrous Metals contain iron and are magnetic. E.g. Mild Steel
Smart Materials
Piezo Transducer ­ Deforms when voltage is applied. Produces a small voltage via a mechanical
Smart Cable ­ Converting mechanical energy into electrical Energy.
Solar Cells ­ Converts solar energy into electrical energy. Many applications, e.g. calculators and
powering satellites. Solar cells can be linked together to form solar modules.
Optical Fibres ­ Glass or plastic fibres, carries light signals which transmit data for communications
and medical applications. Used In place of conductive electrical wire because of better signal and no
interference, also a lighter cable.
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Electronics revision Nicholas wills and Ross
Thermocolour Sheet ­ Changes colour when heated, if touched by hand it causes the material to
change colour. Can be heated by attaching a resistance wire and can be used as a heating element when a
small current is passed through.
Liquid Crystal Display (LCD) ­ Electronic device used to show numbers and text. Each crystal has an
individual electronic connection.…read more

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Electronics revision Nicholas wills and Ross
Batteries are self-contained energy sources that convert chemical energy into electrical energy.
They come in different sizes and voltages, they different internal properties which makes them useful for
different uses.
Zinc-Carbon Battery ­ The most basic battery, it is cheaper than alkali. Suitable for projects that
don't require high outputs.
Alkaline Battery ­Longer-life than zinc-carbon but more expensive, voltage level doesn't fall as
quickly as zinc-carbon. Provides more amp hours.
Silver Oxide ­ Very small 1.…read more

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Electronics revision Nicholas wills and Ross
Capacitors store electrical charge the capacitance value and the working voltage is printed on the
capacitor. Capacitors can be used to create time delays in a monostable, control the frequency of pulse
generators in an astable, smooth the input across the power supply.
1 Microfarad - 1µF = 10-6F (0.000001F)
1 Nanofarad ­ 1nF = 10-9F (0.000000001F)
1 Picofarad ­ 1pF = 10-12F (0.…read more

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Electronics revision Nicholas wills and Ross
Similar to diode. Is a bistable device (meaning it has two states and can only be changed by
setting and resetting). A Thyristor stays latched on until its reset by interrupting the current flow through
A thyristor can by switched on by many inputs; tilt switches, vibration switches, membrane
switches, reed switches, piezo transducers.
Relays use electromagnetism to allow one electronic circuit to switch on a second circuit without
an electrical connection between them.…read more

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Electronics revision Nicholas wills and Ross
Integrated Circuits
555 IC Monostable
Time period = C*R
The minimum value of R1 should be 1k
The maximum value of R1 should be 1M
The minimum value of C1 should be 100pF
The maximum value of C1 should be 1000µF
The minimum time period is about 0.…read more

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Electronics revision Nicholas wills and Ross
Logic Gates
Logic gates: AND, OR, NOT, NAND, NOR, EXCLUSIVE OR.…read more

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Electronics revision Nicholas wills and Ross
NOR gate Output only high is A and B is low
EXOR gate output will be high when A or B is high
Circuits Made from NAND gates
Astable circuits ­ two NAND gates as NOT gates
Time delay circuits
Latch circuits
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Electronics revision Nicholas wills and Ross
The most popular remote control technology in the home is Infra-Red (IR). The reference to red is
the colour of the longest wave length of visible light. The basic concept with infra-red is the use of
invisible light to carry signals between the remote control and the electronic system that its controlling.
Transmitting signals - An infra-red remote control send out the infra-red light pulses that
represent specific binary values.…read more

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Electronics revision Nicholas wills and Ross
The address code also reduces the chance of the infra-red receiver responding to a remote control
intended for another appliance
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