Key term
CCEA A-Level Technology and Design 8900
Material Selection and Wood
Metals
Plastics
Composite and Emerging Materials
Processing Materials
Product Analysis and Design Communication
Design for Manufacture, Quality and Safety
Electronic Control SystemsOption A
Topic overviewControl systems, feedback and electronics safetyResistors, Ohm's law and power ratingsCapacitors and RC timingPotential dividers, sensors and comparatorsSwitches, pull-up and pull-down resistorsOutput devices and LEDsTransistors, Darlington pairs and thyristorsLogic gates, truth tables and flip-flops555 monostable and astable timers
Microelectronic Control SystemsOption A
Topic overviewMicrocontroller systems, ADCs and DACsStrain gauges and bridge circuitsOptical switches, encoded discs and Schmitt triggersOp-amp amplifiers and gainZener diodes and voltage regulatorsKarnaugh maps and binary countersSeven-segment, LCD and dot matrix displaysPIC flowcharts and programmingDC motors, stepper motors and driver circuits
Mechanical and Pneumatic ComponentsOption B
Topic overviewOpen and closed loop mechanical and pneumatic controlSafe working with compressed air and mechanismsLevers, linkages and momentsGear types and gear trainsPulleys, belts, chains and shaft fixingsCams, cranks and converting motionCompressed air supply and pneumatic valvesCylinders, shuttle valves, restrictors and reservoirsPneumatic circuits for logic, timing and speed control
Mechanical and Pneumatic SystemsOption B
Topic overviewHydraulics, system limitations and plant safetyTorque, work, power and air consumptionVacuum handling, proximity sensors and 5/3 valvesSequential and cascade pneumatic circuitsCam profiles and follower displacement diagramsGear geometry, pulley blocks and ratchetsToggles, treadles, shafts and couplingsFriction, brakes and clutchesBearings, lubrication and seals
Designing and Manufacturing ProductsOption C
Topic overviewResearch, questionnaires and specificationsIdea generation, critiques and computer simulationManufacturing planning and product evaluationCFRP, GRP, Kevlar and tungsten carbideSmart materials, nanotechnology and biophotovoltaicsIsometric, perspective and assembly drawingLaminating, steam bending, cutting and printing processesRisk assessment and product safety lawScales of production, JIT and cell productionQuality assurance, ISO 9001 and continuous improvementDesign influences and intellectual property rights
Product Design in Industry and SocietyOption C
Topic overviewLife-cycle environmental impact and climate changeThe 6Rs, waste and environmental legislationSustainable metals, plastics and degradable polymersProduct life cycles, consumer types and relaunchesCAD, CAM, 3D scanning and quick-change mouldingMarket pull, technology push and market strategyPrice, place and promotionJigs, fixtures and ICT in quality controlDesign for maintenance, inclusion and scale productionRendering, typography and presentationDyson, Baylis, Memphis and Apple
Product Development
Product and System Design and Manufacture
Microelectronic Control Systems
Karnaugh maps and binary counters
- 3 things to know
- A2 1
Overview
Karnaugh maps and grouping rules with worked simplifications, binary and BCD counters, edge triggering, frequency division, counting to five, and switch bounce.
What you need to know
Answer each one before you reveal it.
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Key term
Why are the columns of a three-variable Karnaugh map ordered 00, 01, 11, 10?
Key term
State the rules for grouping 1s on a Karnaugh map.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is a Karnaugh map?
Model answer
A Karnaugh map is a grid of a truth table's outputs, arranged so that terms can be simplified by grouping. A three-variable map has eight cells.
- 2
Why are the columns of a three-variable Karnaugh map ordered 00, 01, 11, 10?
Model answer
The order is Gray code, so neighbouring cells differ in only one variable. Adjacent 1s can then be grouped to eliminate that variable.
- 3
State the rules for grouping 1s on a Karnaugh map.
Model answer
Groups must be rectangles of 1, 2, 4 or 8 cells, made as large as possible. Groups may overlap, and the edges of the map wrap around.
- 4
How is a simplified expression read from a Karnaugh map group?
Model answer
A group gives a term containing only the variables that stay the same across it. The terms from all the groups are then ORed together.
- 5
Simplify X = A·B·C̄ + A·B·C + Ā·B·C using a Karnaugh map.
Model answer
X = A·B + B·C, which can also be written B·(A + C). The pair A·B·C̄ and A·B·C loses C, and the pair A·B·C and Ā·B·C loses A.
- 6
A three-input system outputs 1 whenever at least two of its inputs are 1. Give its simplified expression.
Model answer
The expression is X = A·B + A·C + B·C. Three overlapping pairs on the map all share the cell where A, B and C are 1.
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