crowbar circuit OrCAD simulation

Discussion in 'General Electronics Chat' started by Skyland, Jul 15, 2014.

  1. Skyland

    Thread Starter New Member

    Jul 1, 2014
    28
    0
    I have a couple of issues with the simulation;

    1. : the zener diode has Vz at 4.7V, it is not behaving as expected since it is reducing the supply voltage by 4.7 instead of setting it to that voltage.
    2. : the SCR is not triggering and short circuiting the PSU.
    3. : Is there a way to add a spice model to a thermal fuse in capture.
    4. : Any recommendations on the values of the resistors and capacitor used?
     
  2. Sensacell

    Well-Known Member

    Jun 19, 2012
    1,127
    266
    The SCR must be connected directly across the PSU output to effectively crowbar.

    What voltage do you want the output limited to?
    i.e. what is the nominal output voltage, and the maximum?
     
  3. Skyland

    Thread Starter New Member

    Jul 1, 2014
    28
    0
    the resistor R2 is treated as the output device.
    the maximum voltage should be 16v and the the minimum is 3.3v.
     
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