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3.1.4 Systems approach to designing - Coggle Diagram
3.1.4 Systems approach to designing
Inputs
- a component that manually triggers a system.
Light sensors
(Light dependant resistors LDRs) - Resistance increase in the dark and decrease in the light. No polarity
temperature sensors
(thermistors) - resistance changes with change in temp. No polarity
Pressure switches
- detect pressure from being pushed, can preform on/off tasks. e.g. alarm systems
Pressure sensors
Push to make switch
- the 'legs' of the switch are only connected when the switch it pressed (normally opened). No polarity. Uses: Doorbells, keyboards
Push to break switch
- the 'leg' only disconnect when pressed (normally closed). No polarity. Uses: alarm systems, control systems, shower head systems
Toggle switch
- Off and on position, once switched on they stay on until switched again. Uses Lighting, power switches.
Outputs
- a component added to a system
Buzzers
- high pitch buzz created by fast oscillating electromagnetic parts. Has polarity. Uses: alarm systems, door entry...
Speakers
- Range of sound available, variety of power ratings, variety of frequency responses (bass, treble). Uses: headphones, music systems, radios
LEDs (light-emitting diodes
- low voltage, low power consumption, long-lasting, hard to chnage. Produces light connected by an anode (+ve) and cathode (-ve). Has polarity. Uses: torches
Lamps
- Produce light, cna be brighter than LEDs, less economical due to heat loss, easily hcnaged, not long lasting. Uses: hoursehold lamps, car headlamps.
Processes
Timers
- timing devices used to preform a specific task in electronic systems. Small and cheap to produce.
Monostable device
- output turned on for a set period of time then goes off. Monostable bc is only stable on off position.
Uses: automatic door; sensor detects movement, triggers of the monostable process to turn on for a few seconds. During the time, a motor opens the doors.
Astable device
- constantly fluctuates between on & off states. Uses: drivers seatbelt alarm; sounding a buzzer on/off for a second until seat belt is secure.
Counters
- counting devices help tally how many times an event occurs. Can be triggered with either a monostable or astable input.
e.g. 4017-decade counter, 4026-7 segment display decoder-driver = impulses result in number on display increasing by 1.
Decision making
- a circuit may have to make a decision about a situation. e.g. street light timing; the system detects how much voltage is being received from the LDR and compares that to a pre-determined level noted as 'dark enough' to turn on.