11.1.9

Components

Test yourself

Input Transducers

An input transducer is a circuit that turns a variable outside of the circuit, such as temperature or light, into an electrical signal. Themistors and light dependent resistors (LDR)s can be used to make input transducers.

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Thermistors

  • A thermistor is a component whose resistance changes with its temperature.
  • Usually increasing temperature decreases the resistance.
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LDRs

  • A light dependent resistor (LDR)s resistance changes with light intensity.
  • Usually increasing light intensity decreases the resistance.

Making Input Transducers

Putting a thermistor (or an LDR) in a potentiometer instead of a variable resistor makes a simple input transducer (component that turns a variable into an electrical signal).

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LDR

  • When the light intensity changes, the resistance of the LDR will change.
  • The change in resistance of the LDR changes the potential difference across the resistor.
  • This changing potential difference is the electrical signal produced.
Illustrative background for ThermistorIllustrative background for Thermistor ?? "content

Thermistor

  • When the temperature changes, the resistance of the thermistor will change.
  • The change in resistance of the thermistor changes the potential difference across the resistor.
  • This changing potential difference is the electrical signal produced.

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