Electronic systems and programmable components
边玩边学
回答这些题目来赚取能量，然后钓鱼探索。无需账号。
给教育者： 面向 Electronic systems and programmable components（Design and Technology，Core Technical Principles）的即用型课程幻灯片, 复习笔记——用在你的课堂上，或将该知识点作为学习者可实时游玩的互动课堂活动来运行。
课程笔记
Electronic systems
- Inputs provide information, a process interprets it or applies logic, and outputs produce an indication or action. Switches, LDRs, thermistors and PIR sensors are examples of inputs; LEDs, sounders, motors and displays are outputs in this functional model. Power supply and interfaces are needed in addition to the three information-flow blocks.
- An LDR changes resistance with light, a thermistor with temperature, and a PIR sensor responds to changes in received infrared radiation used to infer relevant movement. Sensor types and conditioning matter; a sensor label does not define a controller-ready voltage range or detect every possible condition.
Information flows through a system
Components
- Resistors provide resistance and dissipate energy when current flows. Transistors can switch or amplify in suitable circuits; ordinary rectifier diodes are often modelled as forward-conducting and reverse-blocking within their intended range. Capacitors store electrical energy through separated charge. Device ratings and circuit context matter.
- A relay is an electrically operated switch, often a coil moving contacts, with specified control and contact ratings. A potentiometer can function as a three-terminal adjustable divider or a variable resistance with suitable terminal connections. Neither component is fully described by saying small current switches large current or merely variable resistor.
- LED current must be controlled appropriately. A suitable series resistor is common with a constant-voltage source; integrated current limiting or a dedicated current driver can be alternatives. Ideal example: (9 − 2)/0.020 = 350 Ω. This is arithmetic, not a complete component choice; verify assumptions, standard values, tolerance and ratings.
Ideal LED arithmetic is one step
Circuit calculations
- Use V = IR in the stated resistor model with volts, amperes and ohms. Series resistances add: 100 + 220 = 320 Ω. With an ideal 6 V source and no other resistance, I = 6/320 = 0.01875 A = 18.75 mA. The same current flows through the series branch.
- Parallel branches connect across common nodes and share their voltage, while current divides according to branch behaviour. Series and parallel describe connections, not simply how components are spaced on a board.
- Ideal LED example: supply 6 V, assumed forward drop 2 V and target current 20 mA = 0.020 A. R = (6 − 2)/0.020 = 200 Ω. A real device’s forward voltage and current vary, and component power, tolerances and supply limits still require checking.
A single series resistor branch
Programmable components
- A microcontroller integrates processing, memory and input/output functions. A program can read a signal, compare it with a condition and command an output. Many flash-based devices can be reprogrammed, but not every controller has the same update method, memory or capabilities.
- The illustrated button decision shows one pass: read the defined button state, test whether pressed, then command the alert on or off. A continuing monitor must repeat the decision and address real input behaviour, timing and startup conditions. The flowchart shows program logic rather than electrical wiring.
- Programmability can support behaviour changes without redesigning hard-wired logic, but cost, timing, power and development effort depend on the task. A GPIO command does not imply that a pin can directly supply any motor or sounder; use an appropriate interface and driver for the actual hardware.
One pass through a button decision
Making circuits
- A solderless breadboard can support suitable prototype circuits, but its connected contact groups and ratings need to match the circuit. PCBs provide designed conductive tracks and mounting arrangements for prototypes or final products. Check the intended connections rather than copying physical spacing as if it were a schematic.
- Use the supervised assessed workshop procedure for assembly and tests. Hot equipment can burn, and rosin-based flux fume can harm health, requiring suitable control. General ventilation wording alone is not a complete fume-control plan. Conceptual calculations here do not replace equipment instruction or component selection.
A model needs a suitable implementation
Potential dividers and sensing
- For an ideal unloaded two-resistor divider, output measured across the lower resistor is Vs × Rlower/(Rupper + Rlower). Equal 10 kΩ resistors across 6 V give 3 V. Identify the reference node and which resistance is upper or lower before using the formula.
- If one resistance changes with light or temperature, output can change with that input. Its direction depends on placement, and output loading changes the ideal divider result. Sensor resistance and controller input requirements must suit the intended operating range.
Read an ideal unloaded divider
幻灯片
练习题
免费预览——35 题中的 8 题。注册即可查看全部。
1.What is an input device?
Easy- Aa device providing information, from a sensor or human control
- Ba motor
- Ca display
- Da buzzer
2.What is an output device?
Easy- Aa switch
- Ba sensor
- Ca battery
- Da component that responds, such as an LED
3.What does a resistor do?
Easy- Acreates light
- Bamplifies sound
- Climits the flow of current
- Dstores charge
4.What does an LED do?
Easy- Alimits current
- Bemits light
- Cstores charge
- Dsenses heat
5.What is a thermistor?
Easy- Aa resistor whose resistance changes with temperature
- Ba light sensor
- Ca switch
- Da motor
6.What does a transistor do?
Easy- Astores charge
- Bmakes sound
- Csenses light
- Dacts as an electronic switch or amplifier
7.What does a diode do?
Easy- Amakes light
- Bsenses heat
- Callows current in one direction
- Dstores charge
8.What does a capacitor do?
Easy- Aproduces sound
- Bstores electrical charge
- Climits current
- Dsenses light
历年真题
该知识点的历年真题练习即将推出。
即将推出