Output Devices
- An op-amp circuit creates a constant gain or amplification in voltage or current
- An output device may be required to monitor the output of an op-amp circuit
- Examples of these are:
- Transducers (a device that changes energy from one form to another)
- A diode
- A microphone
- A loudspeaker
- Digital meter (eg. voltmeter)
- Analogue meter
Calibration of Digital and Analogue Meters
- When digital or analogue meters are used as output devices for measuring the output of an op-amp (eg. voltmeters), calibration may be needed
- This is because the output voltage of an op-amp is unlikely to be exactly proportional to the physical quantity being measured eg. temperature
- With a digital voltmeter, calibration for temperature is done by placing the temperature sensor and a thermometer in a water bath at a number of different temperatures
- A calibration curve is then used to change any voltmeter reading into a value for the physical quantity being measured (ie. temperature)
- Therefore, a scale can be obtained
- For example, an increase of 2 V = increase of 0.5 oC
- Calibration curves are often used to convert measurements made on one measurement scale to another measurement scale
- With an analogue voltmeter, calibration is done in the same way except the result will cause a change in the linearity (linear proportionality) of the scale
