ECT 2440 Chapter Notes - Chapter 9: Electric Current, Photodiode, Differential Amplifier
Document Summary
Overview of computer-based instrumentation: physical phenomena such as temperatures, angular speeds, displacements, and pressures produce changes in the voltages, currents, resistances, capacitances, or inductances of the sensors. If the sensor output is not already a voltage, signal conditioners provide an excitation source that transforms the changes in electrical parameters to voltages: the conditioned signals are input to a data-acquisition (daq) board. Sensors: in which vsensor is the voltage produced by the sensor, k is the sensitivity constant, and m is the measurand. Equivalent circuits and loading: because of the current owing through the circuit, the amplifier input voltage is less than the internal voltage of the sensor. Sensors with electrical current output: usually a current-to-voltage converter (also known as a transresistance amplifier) is used to produce an output voltage that is proportional to the photodiode current. Variable-resistance sensors: other sensors produce a changing resistance in response to changes in the measurand.
