PURPOSE: To obtain a frequency-voltage converting circuit having satisfactory stability and accuracy with simple constitution, by connecting a resistance and a capacitor to the output terminal of an integral network for a monostable multibrator.

CONSTITUTION: A monostable multivibrator consists of an exclusive integral network 11 and a resistance R1 and a capacitor C1 which are connected in series between a power supply VCC and zero potential. With application of a pulse signal ei1 of a frequency (f) to the input of the network 11, a signal e0 is delivered. The ON time of the signal e0 is proportional to the product of C1 and R1, and the height of ON-voltage is about Vec. The means value E1 smoothed by a smoothing resistance R2 and a capacitor C2 is shown as E0= f.LK.C1. C1.R1.VCC (K1: constant) and proportional to the frequency (f) of the input pulse signal. The circuit 11 is responsive to a trigger pulse signal ei2, and accordingly the input will do with the trigger pulse. Then the signal E0 is amplified by a DC ampliier 12. Thus the frequency-voltage conversion is possible with satisfactory stability and acuracy.