NOTES

• Electronic systems:

  • An electronic system is a series of parts or components that control a task or activity
  • Many products contain electronic systems
• Subsystems:

  • Subsystems or subtasks are events or tasks that happen within a system
  • A car’s systems include:
  • Steering
  • Braking
  • Electrical
  • Power and drive
  • Entertainment 
  • Navigation
  • Safety
• Systems diagram:

  • Explaining how a system works can be confusing so a simple block diagram is used
  • Separate inputs, processes, decisions and outputs are placed in individual boxes
  • They are linked with arrows to create a system or subsystem
  • The arrows show the direction (flow) within the system
• systems diagram

  A) nput

  B) rocess

  C) utput

  
• Open loop systems:

  • Open loop systems do not make decisions based on feedback
  • A toaster heats bread for a set period of time
  • It cannot predict the perfect coloured toast
• Closed loop systems:

  • Feedback is used to make a decision
  • Diamond boxes represent decisions
• Closed loop system

  
• Flowcharts:

  • Flowcharts are a more detailed way to graphically represent systems
  • They can also be used when programming microcontrollers
• Flowchart symbols:

  A) tart

  B) rrows

  C) nput

  D) utput

  E) rocess

  F) ecision

  
• Circuits and symbols:

  • Specific symbols are used to represent components in an electronic circuit
  • Circuit symbols are connected in a particular way to assist understanding in a clear layout
  • It is known as a schematic diagram and is a visual representation of the circuit but not a real-life diagram 
• Input components:

  • Systems and devices are triggered either manually or automatically using switches and sensors
  • Switches are a common form of input
  • Sensors can detect heat, light, movement and sound
• Inputs:

  A) oggle

  B) ake

  C) reak

  D) ight

  E) hermistor

  F) ressure

  
• Connecting inputs:

  • Most input components, especially sensors, work best in a potential divider
  • The input is connected to both the positive and negative of the power supply through appropriate components
  • It helps to provide a consistent signal to an input pin
  • A resistor is used to pull-up or pull-down an input pin to avoid it floating, which can cause erratic errors
• Analogue components:

  • Analogue components give out varying signals
  • A potential divider is used to provide the desired voltage in response to changing environmental conditions
  • For example, a street lamp needs to be turned on at dusk
  • The dark detector below uses a variable resistor which allows the sensitivity of the device to be adjusted
• Output components:

  • Output components change electrical energy into light, sound, heat, movement and so on
  • Some output components require lots of energy to operate, e.g. motors and heating elements 
• Output components:

  A) iode

  B) amp

  C) uzzer

  D) peaker

  
• Using high-power outputs:

  • Some output components require more power than the processing components in the circuit can provide
  • Transducer drivers are used to increase the power available
  • These include transistors such as a Darlington pair or field-effect transistors, and operational amplifiers 
  • Relays can be used to operate a high-powered circuit with a low-powered trigger