Fault finding

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1. The voltage that appears between the base and emitter of a silicon transistor operating as a linear amplifier will normally be: a) less than 0.2V b) 0.2V to 0.4V c) 0.4V to 0.6V d) approximately 0.6V.

2. With a PNP transistor used as a linear amplifier, the collector voltage will normally be: a) more positive than either the base voltage or the emitter voltage b) more negative than either the base voltage or the emitter voltage c) more negative then the base voltage but positive with respect to the emitter d) more negative than the emitter voltage but positive with respect to the base.

3. When a transistor used as a saturated switch is in the 'on' state, the voltage between the collector and emitter will usually be: a) less than 0.5V b) approximately 0.6V c) between 1.2V and 2.2V d) more than 5V.

4. The diagram shows a test being carried out on a silicon diode. The typical resistance indicated on the meter should be: a) less than 100 ohm b) between 100 ohm and 10 kohm c) between 10 kohm and 1 Mohm d) greater than 1 Mohm.

5. In the circuit shown below, the transistor has been found not to be faulty. What fault is present? a) R1 open-circuit b) R4 open-circuit c) C2 open-circuit d) L1 open-circuit.

6. In the circuit shown below, what fault is present? a) IC1 faulty b) C3 short-circuit c) TR1 base-emitter open-circuit d) TR1 collector-base open-circuit.

7. Logic probes usually incorporate a monostable pulse stretcher in order to: a) reliably indicate the presence of short duration pulses b) reliably indicate a logic signal that is slowly changing c) prevent erroneous logic indications when signals are very noisy d) provide a permanent logic 0 indication when no signal is present.

8. A logic probe is used to detect a fault in a logic circuit. If both the 'low' and 'pulse' LEDs are illuminated which one of the following waveforms will be present at the probe tip? a) A b) B c) C d) D.