peace be upon you all

I have a good idea for you ...

you may apply a full wave rectified signal on the SCR and thus the SCR will turn off after stop triggering and reaching the Zero Crossing stage ...

I'm ready for any help ..its my graduation project..

 

Welcome to the forums.

Your post was in this thread - http://forum.allaboutcircuits.com/showthread.php?t=32955

You supplied some information germane to the thread, but seem to wish help for an unstated project. Give us the details regarding your project and we may be able to help.

 

I saw a baseball thrower that worked that way. The DC signal went to zero, thus allowing the SCR (which were the power drive components to motors) to turn off reliably. If there had been the slightest bit of capacitance the circuit would have died.

It was a weird one to analyze.

 

It is very common to place an SCR between the positive and negative terminals of a bridge (SCR Cathode to Neg, SCR Anode to Pos) and have control of the AC current by means of phase triggering of the SCR.