Basic Electronics Paper 2,Nov/Dec 2015

Question 3

  1.  


    (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.