VOLTAGE_TO_FREQUENCY_CONVERTER

Published:2009/7/9 5:42:00 Author:May | From:SeekIC

This circuit can accept positive or negative or differential control voltages. The output frequency is zero when the control voltage is zero. The 741 op amp forms a current source controlled by the voltage EC to charge the timing capacitor C1 linearly. NE555 is connected in the astable mode, so that the capacitor charges and discharges between 1/3 VCC and 2/3 VCC. The offset is adjusted by the 10-K potentiometer so that the frequency is zero when the input is zero. For the component values shown: f≈ 4.2 EC kHz. If two dc voltages are applied to the ends of R1 and R4, the output frequency will be proportional to the difference between the two voltages.



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