Frequency-to-voltage converters are electronic devices that convert current signal inputs to proportional voltage outputs. They include an operational amplifier for simple linear signal processing and a small resistor-capacitor (RC) network for removing frequency-dependent ripples. Frequency-to-voltage converters can receive AC and DC voltages, frequencies and pulses, and other specialized waveforms from devices such as encoders, tachometers, timers, relays and switches. Devices with integral filters allow some signal frequencies to pass while attenuating others. Devices with low pass filters allow signals that are below a cutoff frequency to pass while blocking signals that exceed the threshold.  Frequency-to-voltage converters with programmable filters are also available.

Device specifications for frequency-to-voltage converters include the number of analog channels and the number of differential channels. When single-ended outputs are available, suppliers often specify the maximum number of analog channel outputs as twice the number of differential outputs. Differential channels, which have two inputs, define the voltage as the signal to process between the two inputs. Other device specifications for frequency-to-voltage converters include maximum output voltage, accuracy, and signal isolation. Accuracy, which is represented as a percentage of a full measurement range, depends on factors such as signal conditioning linearity, hysteresis, and temperature. Signal isolation can be achieved through optical isolation, magnetic induction, or the use of capacitors.

Frequency-to-voltage converters are available in a variety of form factors. Some devices mount on integrated circuits (ICs), standard DIN rails, or printed circuit boards (PCBs) that attach to enclosures or plug into computer backplanes. Others bolt into walls, cabinets, enclosures, or panels. Rack-mounted units fit inside a standard 19” telecommunications rack. Modular styles include stackable units that dock in bays, slots, or boxes. Benchtop or freestanding frequency-to-voltage converters often feature full casings or cabinets and integral interfaces. 

Frequency-to-voltage converters are used in a variety of industries and applications. For example, vehicle-monitoring applications use frequency-to-voltage converters to evaluate the response times of clutches, air-conditioning compressors, and anti-lock braking systems. Frequency-to-voltage converters are also used in driveline analysis and to monitor and control engine speeds. Other applications for frequency-to-voltage converters include flowmeter monitoring, machine analysis and control, and response time evaluation.