Electrics

• Lamp


  An output device that produces light
• Lamp


  • Result of heat when current flows through it
• Electric current is the flow of electric charge through a conductive medium (e.g. wire)
• Amps are the unit of current
• Ohm's law


  States current flowing through resistor = voltage across the resistor / resistance
• Types of electrical current

  • AC (Alternating Current)
  • DC (Direct Current)
• AC (Alternating Current)


  • Changes direction periodically
  • Usually has an oscillating voltage that reverses with it
  • Used in electrical motors
• DC (Direct Current)


  • Flows in one direction
  • Many digital electronic products run using DC
• Mains electricity


  Electricity supplied at 230V AC in the UK via sockets and three-pronged plugs
• Battery


  A device that converts chemical energy into electrical energy
• Switch


  An input device used to either make or break a circuit
• Relay


  An electrically operated switch used to switch a large load current from a much smaller control current
• Motor


  A device that converts an electrical signal into rotary motion
• Solenoid


  An output device that converts electrical energy into mechanical movement through the use of electromagnetism
• Buzzer


  An output device that uses an internal oscillator to produce sounds
• Bell


  An output device that produces sound using electromagnetism
• USB adaptors can convert AC from mains to DC
• Main types of power supply

  • Mains electricity
  • Batteries
• Mains electricity


  • Cheap
  • Available widely
  • Not portable
  • Limited sockets
  • Could be unsafe and lead to electric burns/shocks
  • Can cause fires
• Batteries


  • Portable
  • Can be put in packs for certain voltages
• Peripheral Interface Controller (PIC)


  A type of microcontroller
• Driver


  A component (or complete sub-system) that increases a signal from the process block to the output block of the system
• Transistor


  A device that acts as a current amplifier for outputs such as lamps and buzzers
• Field effect transistor (FET)


  A digital voltage amplifier
• Output component


  A component that turns an electrical or electronic signal into a visible sign, such as light, sound or movement
• Light-emitting diode (LED)


  A component that produces light when current flows from the anode to the cathode
• 7 Segment display

  A package of LEDs arranged so that numbers can be displayed
• Piezo sounder


  A component that converts an electric signal into sound using the piezoelectric effect
• Discrete component


  An individual or separate component
• Resistor


  A component that reduces the flow of current in a circuit
• Capacitor


  A component that stores electrical charge
• Analogue signals vary continuously over time and can take any value within a given range
• Digital signals are pulses of information that are high (1) or low (0)
• Digital signals can carry more information per second than analogue signals and are also better quality, as seen in information contained on CDs and MP3 files