firebottle

2 definitions found

firebottle - Free On-line Dictionary of Computing (26 May 2007) :

  electron tube
  firebottle
  vacuum tube
  
     <electronics> (Or tube, vacuum tube, UK: valve, electron
     valve, thermionic valve, firebottle, glassfet) An electronic
     component consisting of a space exhausted of gas to such an
     extent that electrons may move about freely, and two or more
     electrodes with external connections.  Nearly all tubes are of
     the thermionic type where one electrode, called the cathode,
     is heated, and electrons are emitted from its surface with a
     small energy (typically a Volt or less).  A second electrode,
     called the anode (plate) will attract the electrons when it is
     positive with respect to the cathode, allowing current in one
     direction but not the other.
  
     In types which are used for amplification of signals,
     additional electrodes, called grids, beam-forming electrodes,
     focussing electrodes and so on according to their purpose, are
     introduced between cathode and plate and modify the flow of
     electrons by electrostatic attraction or (usually) repulsion.
     A voltage change on a grid can control a substantially greater
     change in that between cathode and anode.
  
     Unlike semiconductors, except perhaps for FETs, the
     movement of electrons is simply a function of electrostatic
     field within the active region of the tube, and as a
     consequence of the very low mass of the electron, the currents
     can be changed quickly.  Moreover, there is no limit to the
     current density in the space, and the electrodes which do
     dissapate power are usually metal and can be cooled with
     forced air, water, or other refrigerants.  Today these
     features cause tubes to be the active device of choice when
     the signals to be amplified are a power levels of more than
     about 500 watts.
  
     The first electronic digital computers used hundreds of vacuum
     tubes as their active components which, given the reliability
     of these devices, meant the computers needed frequent repairs
     to keep them operating.  The chief causes of unreliability are
     the heater used to heat the cathode and the connector into
     which the tube was plugged.
  
     Vacuum tube manufacturers in the US are nearly a thing of the
     past, with the exception of the special purpose types used in
     broadcast and image sensing and displays.  Eimac, GE, RCA, and
     the like would probably refer to specific types such as "Beam
     Power Tetrode" and the like, and rarely use the generic terms.
  
     The cathode ray tube is a special purpose type based on
     these principles which is used for the visual display in
     television and computers.  X-ray tubes are diodes (two element
     tubes) used at high voltage; a tungsten anode emits the
     energetic photons when the energetic electrons hit it.
     Magnetrons use magnetic fields to constrain the electrons;
     they provide very simple, high power, ultra-high frequency
     signals for radar, microwave ovens, and the like.  Klystrons
     amplify signals at high power and microwave frequencies.
  
     (1996-02-05)
  

firebottle - Jargon File (4.4.4, 14 Aug 2003) :

  firebottle
   n.obs.
  
     A large, primitive, power-hungry active electrical device, similar in
     function to a FET but constructed out of glass, metal, and vacuum.
     Characterized by high cost, low density, low reliability,
     high-temperature operation, and high power dissipation. Sometimes
     mistakenly called a tube in the U.S. or a valve in England; another
     hackish term is glassfet.