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5 marksLogic Gates

CAPE Physics Unit 2 · 2011 · Paper 2 · Question 2(a)(ii)

Questions on digital electronics, bistable circuits, flip-flops, logic gates, and waveforms.

On Figure 2 (a), draw connecting wires to show the construction of an S-R flip-flop with inputs I_1 and I_2 and outputs Q and Q_bar. Complete the sequential truth table and describe how this circuit acts as an electronic latch for a burglar alarm.

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Other parts of this question

  1. 2(a)(i)What does the term 'bistable' mean when used in reference to an electronic circuit?[1 mark]
  2. 2(b)Draw the truth table for the circuit using input waveforms A and B and resulting output waveform D shown in Figure 2 (b), and hence state the equivalent logic…[4 marks]
  3. 2(c)(i)What is the frequency of the XOR output?[1 mark]
  4. 2(c)(ii)If the same frequency is input but the other input to the XOR is tied to 5 V, what is the frequency of the output?[1 mark]
  5. 2(c)(iii)The same square wave is applied to one input of logic gate P while the other input is grounded. The output waveform is a flat line at 0 V. State the name of…[3 marks]

More practice: the rest of this paper · more Logic Gates questions · all CAPE Physics Unit 2 past papers