Kg fp 1110 16 solutions exercise 72 deflection of

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Unformatted text preview: 6 Solutions to exercises from Chapter 7 Exercise 7.1 Smallest measurable distance Ultrasonic proximity sensors which have only one ultrasonic transducer, operate alternatively as an emitter and as a receiver. The ultrasonic transducer creates oscillations by means of a connected alternating voltage and emits ultrasonic waves. If the voltage is switched off, then the oscillation of the transducer dies out exponentially. The transducer must stop oscillating before a reflecting signal can be received. The final oscillation time is dependent on the size of the transducer. This does not occur with designs which have separate emitter and receiver transducers. However, neither type of proximity sensor should be used to detect objects at small distances for another reason. Characteristically, the ultrasonic emission from these proximity sensors produces secondary lobes in the near field adjacent to the main emitting zone. If an object approaches laterally within the range of the near field, sensing becomes highly irregular so that no predictab...
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