Thus twhere the total voltage applied
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0 V
Figure 18.34 : Resistance to voltage conversion for a thermistor
| R | |||
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| R | � |
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where V is the total voltage applied, in Figure 18.34 this is shown as 6 V, R the value of the resistance between the output terminals (10 k Ω ) and Rt the resistance of the thermistor at the temperature concerned. The potential divider circuit is thus an example of a simple resistance to voltage converter. Another example of such a converter is the Wheatstone bridge.
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Series
resistor
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| Infrared radiation | ||
Figure 18.36 : Optoisolator: infrared radiation is used to transmit signal from input to output circuit
| Signal | Time | Signal | 0 |  |
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| (a) | (b) | Time |
no electrical connections between them. This can be done using an optoisolator ( Figure 18.36 ). Such a device converts an electrical signal into an optical signal, transmits it to a detector which then converts it back into an electrical signal. The input signal passes through an infrared light-emitting diode (LED) and so produces a beam of infrared radiation which is detected by a phototransistor.
18.5.3 Analog-to-Digital Conversion
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