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Considering this circuit, what would happen if T1 and T2 had different firing angles, let's say 45° for T1 and 60° for T2?

Is it the same thing as both of them having 60°? (I think that the circuit is not closed until the second SCR is not fired up).

  • \$\begingroup\$ circuit is not closed ... what does this mean? ... conducting or not conducting \$\endgroup\$
    – jsotola
    Feb 6, 2023 at 23:16

1 Answer 1


The negative half wave of secondary voltage will be rectified by D1 & D2, and the positive polarity will be controlled by T1 & T2.

In case the T1 gate voltage is held (or is a long enough pulse train) after 45º, output current will flow when T2 is switched on (60º). But if T1 gate is activated by a short pulse at 45º, there will be no current to hold T1 switched on because T2 is off; in this condition, when T2 is activated at 60º, no current will flow because T1 is already off.

If you "fire" both T1 & T2 at 60º, current will be established at that angle.


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