crowbar circuit OrCAD simulation

Thread Starter

Skyland

Joined Jul 1, 2014
28
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?
 

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Sensacell

Joined Jun 19, 2012
3,432
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?
 

Thread Starter

Skyland

Joined Jul 1, 2014
28
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?
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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