Abstract: A device for converting an analogous signal having a varying amplitude into a pulse series having a pulse length proportional to the present amplitude value of the analogous signal comprises a capacitor, a sample pulse generator for generating sample pulses of a predetermined frequency, means responsive to the sample pulses for connecting the capacitor temporarily during each sample pulse to a potential proportional to the present amplitude value of the analogous signal and to a direct current source so that the capacitor is charged to a voltage proportional to the amplitude value of the analogous signal and for isolating the capacitor from the direct current source and said potential during the intervals between the sample pulses, a constant current path connected in parallel across the capacitor for discharging the capacitor during the intervals between the sample pulses, a pulse shaping circuit responsive to the current flowing through the constant current path for generating a signal pulse when no current