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Gate source voltage and gate cathode voltage

  1. Aug 4, 2014 #1
    I am studying thyrisors right now. I am really struck at trigger circuit . The book shows gate source voltage and gate chathode voltage as two different things. I fail to understand the difference and significance of them. Please help me out .
     
  2. jcsd
  3. Aug 5, 2014 #2

    NascentOxygen

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    Hi parichay. http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif [Broken]

    Can you provide a jpeg of the schematic and associated text where these are discussed?
     
    Last edited by a moderator: May 6, 2017
  4. Aug 9, 2014 #3
    Here is the image
     

    Attached Files:

  5. Aug 9, 2014 #4
    Notice that the gate is not directly connect to Es trigger voltage source.
    Voltage at thyristors gate is equal to Ug = Es * Ig*Rs. And only if Rs = 0 Ohm then Es = Ug
     
  6. Aug 9, 2014 #5

    jim hardy

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    i think it's a question of grammar and vocabulary, not one of electronics.

    Notice there's no hyphen in "gate source" inferring that's his description of the circle labelled Es, which i'd have called "gate supply" .
    Gate-source is such a common phrase in FET literature it's an easy mistake to make.

    Thyristors have a terminal called cathode but not one called source .
    'Source' is almost synonymous with 'supply', and both could be either noun or verb,
    so i think "gate source" was just a poor if excusably natural choice of wording.

    My 2cents and probably overpriced at that.

    old jim
     
  7. Aug 9, 2014 #6

    sophiecentaur

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    Always good value, Jim.
     
  8. Aug 10, 2014 #7

    NascentOxygen

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    I agree with Jim. [PLAIN]http://physicsforums.bernhardtmediall.netdna-cdn.com/images/icons/icon14.gif [Broken]

    Gate voltage is what you see on the gate terminal, usually it's the gate-to-cathode voltage. The origin of this is typically a voltage source separated from the gate by a resistor network, or a pulse transformer, or opto-isolator, etc., and it's this voltage source that your textbook refers to as the origin or source of the gate drive.
     
    Last edited by a moderator: May 6, 2017
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