Passive components can't introduce net energy into the circuit. They also can't rely on a source of power, except for what is available from the (AC) circuit they are connected to. As a consequence they can't amplify (increase the power of a signal), although they may increase a voltage or current (such as is done by a transformer or resonant circuit). Passive components include two-terminal components such as resistors, capacitors, inductors, and transformers.

  

Resistors

  

Pass current in proportion to voltage (Ohm's law) and oppose flow of current 

• Resistor – fixed value
• • Power resistor – larger to safely dissipate heat generated
  • SIP or DIP resistor network – array of resistors in one package
• Variable resistor
• • Rheostat – Two-terminal variable resistor (often for high power)
  • Potentiometer – Three-terminal variable resistor (variable voltage divider)
  • Trim pot – Small potentiometer, usually for internal adjustments
• Heater – heating element
• Resistance wire, Nichrome wire – wire of high-resistance material, often used as heating element
• Thermistor – temperature-varied resistor
• Humistor – humidity-varied resistor
• Varistor, Voltage Dependent Resistor, MOV – Passes current when excessive voltage present 

Capacitors

  

Capacitors store and release electrical charge. They are used for filtering power supply lines, tuning resonant circuits, and for blocking DC voltages while passing AC signals, among numerous other uses. 

• Capacitor
• • Integrated capacitors
  • • MIS capacitor
  • Fixed capacitors
  • • Ceramic capacitor
    • Film capacitor
    • Electrolytic capacitor
    • • Aluminum electrolytic capacitor
      • Tantalum electrolytic capacitor
      • Niobium electrolytic capacitor
      • Polymer capacitor
      • OS-CON
    • Electric double-layer capacitor
    • • Nanoionic supercapacitor
      • Lithium-ion capacitor
    • Mica capacitor
    • Vacuum capacitor
  • Variable capacitor – adjustable capacitance
  • • Tuning capacitor – variable capacitor for tuning a radio, oscillator, or tuned circuit
    • Trimmer capacitor – small variable capacitor usually for internal adjustments
    • Vacuum variable capacitor
  • Capacitors for special applications
  • • Power capacitor
    • Safety capacitor
    • Filter capacitor
    • Light-emitting capacitor
    • Motor capacitor
    • Photoflash capacitor
    • Reservoir capacitor
    •  
  • Capacitor network (array)
• Varicap diode – AC capacitance varies according to the DC voltage applied 

Magnetic (inductive) devices

  

Electrical components that use magnetism: 

• Inductor, coil, choke
• Variable inductor
• Saturable Inductor
• Transformer
• Magnetic amplifier (toroid)
• Ferrite impedances, beads
• Motor / Generator
• Solenoid
• Loudspeaker and microphone 

Networks

 

Components that use more than one type of passive component: 

• RC network – forms an RC circuit, used in snubbers
• LC Network – forms an LC circuit, used in tunable transformers and RFI filters 

Transducers, sensors, detectors 

1. Transducers generate physical effects when driven by an electrical signal, or vice-versa.
2. Sensors (detectors) are transducers that react to environmental conditions by changing their electrical properties or generating an electrical signal.
3. The transducers listed here are single electronic components (as opposed to complete assemblies), and are passive. Only the most common ones are listed here. 

• Audio
• • Loudspeaker – Magnetic or piezoelectric device to generate full audio
  • Buzzer – Magnetic or piezoelectric sounder to generate tones
• Position, motion
• • Linear variable differential transformer (LVDT) – Magnetic – detects linear position
  • Rotary encoder, Shaft Encoder – Optical, magnetic, resistive or switches – detects absolute or relative angle or rotational speed
  • Inclinometer – Capacitive – detects angle with respect to gravity
  • Motion sensor, Vibration sensor
  • Flow meter – detects flow in liquid or gas
• Force, torque
• • Strain gauge – Piezoelectric or resistive – detects squeezing, stretching, twisting
  • Accelerometer – Piezoelectric – detects acceleration, gravity
• Thermal
• • Thermocouple, thermopile – Wires that generate a voltage proportional to delta temperature
  • Thermistor – Resistor whose resistance changes with temperature, up PTC or down NTC
  • Resistance Temperature Detector (RTD) – Wire whose resistance changes with temperature
  • Bolometer – Device for measuring the power of incident electromagnetic radiation
  • Thermal cutoff – Switch that is opened or closed when a set temperature is exceeded
• Magnetic field (see also Hall Effect in semiconductors)
• • Magnetometer, Gauss meter
  •  
• Humidity
• • Hygrometer
• Electromagnetic, light
• • Photo resistor – Light dependent resistor (LDR) 

Antennas

  

Antennas transmit or receive radio waves 

• Elemental dipole
• Yagi
• Phased array
• Loop antenna
• Parabolic dish
• Log-periodic dipole array
• Biconical
• Feedhorn 

Assemblies, modules

  

Multiple electronic components assembled in a device that is in itself used as a component 

• Oscillator
• Display devices
• • Liquid crystal display (LCD)
  • Digital voltmeters
• Filter 

Prototyping aids 

• Wire-wrap
• Breadboard