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Integrated speed or voltage converter based on LM2917 with frequency or voltage as output

Published on Jan 07 2011 // Acceleration and Speed Sensor Circuits

Integrated speed or voltage converter based on LM2917 with frequency or voltage as output.

Constituted by the LM2917 frequency / voltage conversion circuit as shown. Measured frequency signal received through the potentiometer RP LM2917 1 of feet. RP constituted by the input divider, adjust the position of RP slider can change the input frequency signal amplitude. 12V power supply through R3, the diode VD partial pressure, the A1 to the comparator’s inverting input to provide 0.6V reference voltage. R2 is the output voltage of the load resistor, R2 is the range of 4.3kO ~ 10kO. 0 ~ 10V DC voltmeter in parallel with R2 at both ends, used to indicate the measured frequency values. R4 is an internal regulator of the current limiting resistor, taking R4 = 470O, the steady current
Where, t the time constant of said charge pump: t = R1C1. Can be seen from the above equation, U0 addition to f on, but also with the supply voltage UCC, the time constant t off charge pump. Once the UCC, t is determined, Uo depends only on f, which is the principle of measuring frequency using LM2917.