GCSE Design & Technology CCEA Unit 1 - Electronics

• NPN transistor

  Transistors are semiconductor devices. When a small voltage is present at the base leg (B) it allows current to flow from the collector leg (C) to the emitter leg (E).

  
• BUZZER

  Buzzers are usually of the single tone variety and are normally rated between 6 and 24 volts.

  They are suitable for alarm circuits, test equipment, timing and control.

  
• Light Emitting Diode

  ( LED )

  Introduction to LED'shttps://www.youtube.com/watch?v=KtaWM1ym6lE


  An L.E.D gives off light when current flows through it. Current can only flow through it in one direction, from the anode to the cathode. LEDs must be protected by a resistor to protect it from too much current flowing through it and then becoming damaged/.

  
• Bulbs


  Bulbs are used as a form of illumination or indication and the type commonly used has a filament coil which glows white hot when a current passes through it.

  
• Motors


  This is a device for changing electrical energy into rotational movement.

  
• Potentiometer


  A three terminal resistor that acts as a potential divider. Has a wiper that can be adjusted to give any fraction of the voltage applied across the resistor. Commonly used in volume controls

  
• BATTERY - SINGLE CELL


  Batteries are used to provide power to electronic circuits. They have a chemical inside them which stores electrical energy until it is needed.

  
• Battery - Multi cell


  Batteries are used to provide power to electronic circuits. They have a chemical inside them which stores electrical energy until it is needed.

  
• Thermistor


  Thermistors are suitable for temperature controlled switches and temperature measurements. The resistance of these devices decreases when they are heated.

  
• Light Dependant Resistor (LDR)

  Light dependant resistors are semi conductors that have a low resistance in light conditions and high resistance in dark conditions.

  
• Thyristor

  A thyristor is a latching device. It comes on when a small voltage is present at the gate leg. It can only be turned off again by cutting the power to the anode leg.

  
• DIODE


  Diodes allow current to pass through them in one direction only. It is used for rectifiers in power supplies.

  
• Toggle Switch,

  Rocker switch,

  
  

  Single pole single throw Switch

  (SPST)


  Toggle and rocker switches switches have a lever that is thrown on or off to make or break the connections.

  
• Push to make switch (PTM)


  These are switches that make or break the connection when they are pressed.

  PTM - usually have a red button.

  
• Single pole double throw

  Switch

  (SPDT)

  These switch are always on. When the switch is thrown it connects to a different

  circuit.

  
• Reed

  switch

  This is a glass bead containing 2 metal strips inside it. When a magnet comes near the bead the 2 metal strips are magnetized and touch together to complete the circuit.