Midterms Mam Kaye

• The invention of the _ in _ opened the door to the information age as we know it

  transistor, 1947
• Computers made up of something called __, aka vacuum tubes


  thermionic valves
• The basic working principle of a vacuum tube

  Thermionic emmision
• He created the first vacuum tube using thermionic emission which he called "__"

  John Ambrose Fleming 1904, oscillation valve
• Fleming's device consists of two electrodes, the _ and the _

  Cathode, Anode
• When heated, gives off electrons via thermionic emissions


  Cathode
• This electrode is also called "the plate"


  Anode
• _ are commonly used for rectification.


  Diodes
• "a circuit converting currents from Alternating current (AC) to a direct current (DC)

  The Power Supply
• He added a third electrode, creating the first triode tube

  Lee de forest
• _ is the third electrode which uses vacuum tube as amplifier of electrical signals. Placed between the cathode and anode


  Control Grid
• _ can serve as an on/off switch as well as a signal amplifier 


  Triode
• in _, theres an additional grid called the "screen grid"

  Tetrode
• _ _ is placed between the control grid and anode


  Screen Grid
• _ has an additional grid called the "suppressor grid"


  Pentode
• The _ _ improves the gain of the valve and acts as a screen, insulating the input from the output

  Screen Grid
• At 100 KHz, the _ is difficult to use.

  Tetrode
• Where is the screen grid placed?

  between the control grid and the anode decoupled to the ground
• This is heated by the heater

  Cathode
• Fundamentally used to control the flow of electrons between the cathode and anode


  Control Grid
• _ has a total of 5 elements within the envelope and it provides a high level gain which overcomes the "kink"


  Pentode
• Consists of Cathode, Control Grid, Screen grid, Suppressor grid, and Anode

  Pentode
• the heater and emits electrons into the evacuated envelope

  Cathode
• In Pentode, _ functions as the creator of lower voltage region between screen grid and the anode.


  Suppressor Grid
• Two key concepts of a vacuum tube:

  1. _ _
  2. _ _ _ _

  Thermionic emission. Charge attraction and repulsion.
• The process of Thermionic Emission has many similarities with _ from the surface of a _

  evaporation, liquid.
• related to the absolute temperature as well as a constant "b" indicating the work on electron has to do to escape the surface

  Electron emmision
• _ provides one of the most robust forms of filament when very high anode voltage is used

  Tungsten
• __widely used in vacuum tubes consists of tungsten and 1 to 2% of thorium oxide

  Thoriated Tungsten
• have a layer of a mixture of barium and strontium. They emit electrons profusely

  Oxide Coated Emitters
• One important aspect of vacuum tubes. These are the electrons flowing between the cathode and the anode from a cloud of electrons


  Space Charge
• By far the greatest used. This cathode is coated with a mixture of barium and strontium


  Oxide Coated Cathode
• Anodes are generally made of _

  Nickel
• In most basic form of a vacuum tube, It may have _ grid

  one
• Recite the number of grids per Generic Name (Name - Grid number)


  Triode - 1

  Tetrode - 2

  Pentode - 3

  Hexode - 4

  Heptode - 5

  Octode - 6
• A grid is normally constructed in the form of a _ _

  Gauze Mesh
• The most important components in power supplies are _ _

  Rectifier Diodes
• _ are "unidirectional devices" thats able to produce a DC output voltage.

  Diodes
• ___ or "_" is the standard way of measuring and reporting alternating current and voltage. It is the way to find the average size of a fluctuating signal.

  Root Mean Square or RMS
• The value of a halfwave signal can be determined by the formula:


  Vrms = 1.57Vavg or Vrms = Vpk/2