Question 3
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(a) Draw and label the circuit symbol of the following devices:(i) thyristor;
(ii) diac.
(b) Describe the switching operation for each of the devices in 3(a).
Observation
The expected answers were:
(b). (i) For the thyristor to turn on its anode is made positive with respect to its cathode
and a trigger pulse is applied to its gate.
(ii) The diac is turned on if either a positive or negative voltage applied to either of the
terminals reaches the breakover value.\
Question 3 is a recall question which can be found in several standard textbooks.
Performance of candidates was very poor.