frequency to voltage converter and voltage to frequency converter where an instrumentation system is...
TRANSCRIPT
![Page 1: Frequency to Voltage Converter and Voltage to Frequency Converter Where an instrumentation system is based mainly on capturing voltage signals (analogue](https://reader036.vdocuments.net/reader036/viewer/2022082417/56649d995503460f94a83db9/html5/thumbnails/1.jpg)
Frequency to Voltage Converter and
Voltage to Frequency Converter
Where an instrumentation system is based mainly on capturing voltage signals (analogue multiplexer and A/D) it may be inconvenient to provide separate inputs for pulse or frequency signals. They can be converted to a voltage by a Frequency to Voltage converter circuit, F/V.
(Conversely some systems are designed to capture pluses or frequencies for them voltages can be converted to frequencies, V/F. The integrated circuits used are often the same.)
![Page 2: Frequency to Voltage Converter and Voltage to Frequency Converter Where an instrumentation system is based mainly on capturing voltage signals (analogue](https://reader036.vdocuments.net/reader036/viewer/2022082417/56649d995503460f94a83db9/html5/thumbnails/2.jpg)
Frequency to Voltage converter
The LM331 is a V/F used here as F/V. A pulse train or square wave of at least 3v amplitude. 10kHz produces an output of 10v the linearity is good. However, the circuit has a slow response to input changes
![Page 3: Frequency to Voltage Converter and Voltage to Frequency Converter Where an instrumentation system is based mainly on capturing voltage signals (analogue](https://reader036.vdocuments.net/reader036/viewer/2022082417/56649d995503460f94a83db9/html5/thumbnails/3.jpg)
Frequency to Voltage converter
The operating principle here can be applied to any monostable circuit. The zero crossings of the pulse of frequency signal are used to trigger the monostable, whose fixed width pulses are integrated by the RC filter to produce a dc voltage.The higher the frequency the higher the voltage. A simple circuit like this will need calibration.
![Page 4: Frequency to Voltage Converter and Voltage to Frequency Converter Where an instrumentation system is based mainly on capturing voltage signals (analogue](https://reader036.vdocuments.net/reader036/viewer/2022082417/56649d995503460f94a83db9/html5/thumbnails/4.jpg)
PH4705/ET4305: Voltage to Frequency Converter
In some circumstances sending a analogue signal into a measurement system is not the best solution to a problem, there may be excessive noise or a long distance between sensor and system or simply all the other signals may be digital. One solution is to convert the analogue voltage to a frequency.
It is possible to use Op Amps or other common ICs (e.g. 555 Timer) but a better performance comes from specialist ICs.
![Page 5: Frequency to Voltage Converter and Voltage to Frequency Converter Where an instrumentation system is based mainly on capturing voltage signals (analogue](https://reader036.vdocuments.net/reader036/viewer/2022082417/56649d995503460f94a83db9/html5/thumbnails/5.jpg)
PH4705/ET4305: Voltage to Frequency Converter
The LM331again, this time
as F/V, it offers a highly linear conversion, 0.01% max and wide frequency range, 1to 100kHz in a single simple to use package.
The output is a digital pulse train that is easily interfaced to digital measurement systems.
![Page 6: Frequency to Voltage Converter and Voltage to Frequency Converter Where an instrumentation system is based mainly on capturing voltage signals (analogue](https://reader036.vdocuments.net/reader036/viewer/2022082417/56649d995503460f94a83db9/html5/thumbnails/6.jpg)
PH4705/ET4305: Voltage to Frequency Converter
Typical applications are as shown.
The output of a single sensor (photo-transistor, temperature sensor) is converted to a frequency for transmission to a measurement system.
![Page 7: Frequency to Voltage Converter and Voltage to Frequency Converter Where an instrumentation system is based mainly on capturing voltage signals (analogue](https://reader036.vdocuments.net/reader036/viewer/2022082417/56649d995503460f94a83db9/html5/thumbnails/7.jpg)
PH4705/ET4305: Voltage to Frequency Converter
The internal circuitry is complex and difficult to emulate using simpler devices.
Other V/F:F/V integrated circuit are AD650 and LM2907