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thyristor vs triac

Discussion in 'General Electronics Discussion' started by cjdelphi, Feb 27, 2016.

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  1. cjdelphi

    cjdelphi

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    Oct 26, 2011
    I'm posting this mainly for others, but after a few searches and ebay seller listings many people seem confused...

    While looking for resources to read, most people seem to interchange or use both "triac" and "thyristor" like they are both the same component!

    And to add to confusion "SCR" well a sillicon controlled rectifier can be a triac or thyristor right?

    In short thyristors allow ac to flow in 1 direction, triacs allow ac to flow in both directions, search for thyristor circuits and you'll indeed find triacs not thyristors but a lot of people seem to confuse the two which confused me lol
     
    Alec_t likes this.
  2. Minder

    Minder

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    Both the GE SCR manual and the RCA manuals both refer to Triacs (bidirectional triode thyristor) and SCR's as part of the Thyristor family of semiconductors.
    M.
     
    Last edited: Feb 27, 2016
  3. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    Basically, SCRs and thyristors are for switching dc and triacs for switching ac.
    A believe "thyrisor" is just a fancy name for a high current SCR.

    So a triac and a thyristor are not the same components, but a scr and a thyristor are essentially the same.
     
  4. Minder

    Minder

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    GE were the first developer of the Triac after the SCR development (patent 3,275,909), and they termed it a Bidirectional Triode Thyristor.
    I have the 6th edition of the GE SCR manual, 1st edition 1st pub. 1958.
    They refer throughout to SCR's and Triacs as thyristors devices.;)
    M.
     
  5. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    Thank you for the correction.
    I have never heard anyone referring to a Triac calling it a Thyristor.
     
  6. dorke

    dorke

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    Jun 20, 2015
    What's in a name?

    Before the semi-conductor period,
    "name calling" started with Vacuum-Tubes or Valves.
    As in so many fields we have the Greecks to blame for;)

    They where named by the number of the Electrodes :
    DIODE : DI-ODE ,Di for dual or 2 ,ODE short of electrode
    TRIODE : TRI-ODE ,Tri for 3
    TETRODE : TETR-ODE ,Tetr for 4
    PENTODE : PENT-ODE ,Pent for 5

    Then there were the ones named by "functionality"
    MAGNETRON :Magne-Tron ,Magne for magnet,Tron for Electron.
    CYCLOTRON :Cyclo-Tron, Cyclo for cycle (circle)
    THYRATRON :Thyra-Tron ,Thyra for entrance or gate.

    then came the semis named as follows:

    THYRISTOR :Thyr-Istor ,replacing Tron(from Thyratron above) with Transistor (Thyra+Transistor)

    TRIAC Tri-AC : TRi for 3 pins ,AC for Alternating Current

    DIAC Di-AC : Diode for AC

    S.C.R Silicon Controlled Rectifier a controllable diode( for DC).


    Personally,
    I prefer not to use Thyristor and prefer
    SCR for DC and Triac for AC.:)
     
    Last edited: Feb 27, 2016
    Arouse1973 and Tha fios agaibh like this.
  7. Minder

    Minder

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    Apr 24, 2015
    A Triac If used on DC has to be commutated off, they are just as readily used in AC such as SCR bridge for one etc.?
    Also SCR used back to back for AC use to simulate a triac.
    I guess those that develop them, get to name them.;)
    M.
     
  8. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    Seem silly to me to use generic names like thyristor or vacuum-tube when referring to components.

    It's like walking into a grocery store and asking for a can of vegetables.
     
  9. dorke

    dorke

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    Jun 20, 2015
    Absolutely,
    SCRs are used in AC application.

    The inventors do it lovingly like naming a new born baby...;)
     
  10. dorke

    dorke

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    Jun 20, 2015
    Well ,
    Imagine asking for a "Modern Aladdin's Lamp";)
    here goes a true gem,enjoy:)
     
  11. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    Those confounded newfangled inventions. Lol

    (Good video but could only stand about 5 minutes of it)
     
  12. sureshot

    sureshot

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    Jul 7, 2012
    I thought a triac was two thyristors back to back in a single package ?
     
  13. dorke

    dorke

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    Jun 20, 2015
    The interesting part stars after 5:00...;)
     
  14. Herschel Peeler

    Herschel Peeler

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    Feb 21, 2016
    Thyristor is a general group of transistors that includes SCRs TRIACs, SCSs and such.
     
  15. cjdelphi

    cjdelphi

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    Oct 26, 2011
    À SIlicon Controlled Rectifier (SCR) is going back to William Shockleys 4? Layer diode is a general group of transistors but a thyristor and triac are not the same thing even though they're both SCRs
     
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