Abstract: A circuit arrangement for controlling a rotary-magnet measuring instrument (6) by an input voltage via a controlled source of current has a first amplifier (difference amplifier 1) with a first negative-feedback resistor (R.sub.2) and a first input resistor (R.sub.1). In order to linearize the approximately S-shaped characteristic curve of the rotary-magnet measuring instrument (6), the controlled source of current is developed with a characteristic curve which is defined as consisting of three straight line segments of differing slope. For this, a second amplifier (difference amplifier 8), controlled as a function of the input voltage and a semiconductor path controlled by it (2nd npn-transistor 12) which lies in series with the first input resistor (R.sub.1) are provided. One input (10) of the second amplifier is connected to a constant voltage divider (divider resistors R.sub.3, R.sub.5) and via a second negative-feedback resistor (R.sub.