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Electronic Devices and Circuits - Engineering

Q1:

SCR can be turned on by
  1. applying anode voltage at a sufficient fast rate
  2. applying sufficiently large anode voltage
  3. increasing the temperature of SCR to a sufficiently
  4. applying sufficiently large gate current.

A 1, 2, 4 only

B 4 only

C 1, 2, 3, 4

D none

ANS:C - 1, 2, 3, 4

If we apply the anode voltage above breakover voltage of SCR, SCR can be triggered. Also by sufficiently fast rate of rise of anode voltage and large gate current will trigger SCRon. During forward blocking most of the applied voltage appears across reverse biased junction J2. This voltage across J2 associated with leakage current may rise temperature of this junction. With increase in temperature, leakage current through junction J2 further increases and this cumulative process may turn on the SCR at some high temperature.