Charateristics of the SCR NTE5411 Thyiristor

Discussion in 'Homework Help' started by Nara Shikamaru, Nov 24, 2007.

  1. Nara Shikamaru

    Thread Starter Active Member

    Nov 24, 2007
    92
    3
    Hi everybody!!...im newbie so i need some proffesional help here....i need to calculate this circuits but i think im doing the calculus wrong cause they doesnt work...i need to trigger a SCR NTE5411 (Thyristor) to activate a 12V 0.2A Fan motor marked RL on the circuits...please....help me out here...they are very short circuits....need some help specially in the 2nd and 3rd circuit....well...grettings from Venezuela...thanks already!!
     
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Can you show us the work you've already done? Show us where you are getting stuck?
     
  3. Nara Shikamaru

    Thread Starter Active Member

    Nov 24, 2007
    92
    3
    The 1st and 2nd circuit i tested them...but i used Rg1= 22K and Rg2= 1.2k and when i push the button it didnt trigger the SCR to activate the motor....so read the circuits...i think im miscalculating....i guess it must be some other values for the resistors!!.....in the 3rd cicuit...that im completely stuck....i dont know if the AC voltage is 12VAC (cause the motor is a 12V)...and i dont know if it must be 60Hz or some other frecuency....and even less i dont know how to obtain the triggering and conduction Angle in the 3rd circuit by the Graphs in VRL and VRG....
     
  4. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Do you have access to the following:

    battery voltages?

    trigger voltage for the SCR you are using?
     
  5. Nara Shikamaru

    Thread Starter Active Member

    Nov 24, 2007
    92
    3
    hi there!!...the first circuit i already got it good...the SCR 5411 needs minimun 200uA of gate current to trigger and between 20uA and 50mA of holding current....so i finally calculated for 4mA of gate currrent i used
    Rg1=2.7K and Rg2=10k to obtain 1V of gate voltage and 4mA of gate current....the Bat i used 12VDC cause the Fan motor is a 12V 0.13A....the second circuit im doing it right now....its almost the same..BUT...the 3rd circuit....that i still dont get it....i supposed that the Vac must be 12VAC??....or less?....and 60Hz??....and the variable VDC must be 0-3V???.....i really could use some help in the 3rd circuit!!...especially in calculating that stuff about conduction and triggering Angle!!...thanx!!
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    A test for the function of an SCR is to place a meter's leads on the SCR in the ohms function - red lead to the anode and black to the cathode. Use a clip lead to short the anode lead to the gate, and the SCR should go into conduction.
     
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