#amplifier  electronic equipment that increases strength of signals passing through it
  supertype:  electronic_equipment  equipment that involves the controlled conduction of electrons (especially in a gas or vacuum or semiconductor)
  part of:  public_address_system  radio_receiver  stereo_system
  subtype:  audio_amplifier__audioamplifier  an amplifier that increases the amplitude of reproduced sound
  subtype:  boosters__booster_amplifier__boosteramplifier__booster_stations__relay_links__relaylink__relay_stations__relay_transmitters  an amplifier for restoring the strength of a transmitted signal
  subtype:  maser  Microwave Amplification by Stimulated Emission of Radiation; amplifier that works on same principle as a laser and emits coherent microwave radiation
     subtype:  gas_maser__gasmaser  a maser in which microwave radiation interacts with gas molecules

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