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Electronics Paper 2, May/June 2009  
Questions: 1 2 3 4 5, 6 &7 8 9 10 Main
General Comments
Weakness/Remedies
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Question 10

(a)        Define the term transducer.

(b)(i)    State one control system that uses a transducer.
   (ii)    Briefly explain how the transducer named in (b) (i) is used in controlsystems.

(c)         List four types of transducer.

_____________________________________________________________________________________________________
OBSERVATION

The expected answers were:

(a)        A transducer is a device that converts energy from one form to another.                  

(b)(i)    Control systems that use transducers include:           
            -     Speed control system
            -     Position control system.
            -     Pneumatic control system.

   (ii)    -     Speed control – a tachometer converts speed to voltage that is then
                  compared with set reference to provide control signal.

-     Position control: a potentiometer converts position to voltage, which is then       compared with set reference to provide desired control signal.

-     Pneumatic control:  pneumatic valve springs convert pressure to voltage for       comparison with a set reference to obtain the desired control signal.

(c)       Types of transducer
            -      Loudspeaker
            -      Microphone
            -      Tachometer
            -      Motor
            -      Generator
            -      Piezo-electric crystals
This question was on control circuit.  The question was popular.  Candidates that attempted this question answered every part well.

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