A voltage to frequency converter with a control range of 1:1000 can be easily constructed by using the IC TSC9402. The given component values in the circuit produces a conversion factor of 1kHz/1V. The input voltages from 10 mV up to 10 V are converted to frequencies 10 Hz up to 10 kHz. This conversion can be changed if desired through the potenti
ometer P1. The circuit has two outputs: a sharp pulse comes out from pin 8 with the main output frequency. A clean squarewave comes out of pin 10 but its frequency is half of the output frequency at pin 8. Calibration: use an accurate frequency counter and adjust P1 so that an input level of 10 mV will produce a signal of 10 Hz at the output. One area of application for this circuit is the telemetry. In this case, telemetry of voltage values. By converting the voltage value to a frequency, the value can be transmitted either via a coaxial cable or radio. Wireless telemetry method using radio, can be realized by using the output of this circuit to modulate the carrier signal of a transmitter. It is not possible to use directly the output frequency of this circuit since it produces only a maximum of 10 kHz (equivalent to a measured voltage of 10 volts at its input). The following diagram shows how to use the circuit for remote measurements using a coaxial cable. The technique is limited to several meters though. The distance can be increased by using a signal amplifier. The diagram on the right shows the circuit modulating a transmitter to transport the measured value via radio signals. This technique allows remote telemetry over very long distances. If the signal is repeated via a satellite transponder, the telemetry can be done worldwide.