Abstract: To derive a stable square-wave signal from a measurement-signal voltage obtained from a voltage divider and containing a DC component and an AC component, the low end of the voltage divider is grounded through a load resistor shunted by the series combination of a resistor and a grounded capacitor. The low end is connected through the resistor to the negative input of a comparator and through an additional resistor to the positive input of the comparator. This positive input is also connected through a feedback resistor to the output of the comparator. The low end is connected to the supply voltage (U.sub.V) via a second voltage divider whose first resistor is formed by a controllable, temperature-stabilized zener diode connected to the supply voltage (U.sub.V) through the second resistor of the second voltage divider. The measurement-signal voltage (U.sub.M) obtained from the tap of the first voltage divider is applied to the control electrode of the zener diode.

Abstract: A circuit for deriving a temperature-independent square-wave signal from a measurement signal which consists of a DC component and an AC component and which is taken across a magneto-resistor exposed to an alternating magnetic field. The circuit has a controllable impedance, a timing section with a relatively long time constant, and operational amplifiers with FET inputs.

Abstract: A circuit for amplifying a measurement signal having an AC component and obtained from the tap of a voltage divider which is connected via a dropping resistor to a supply voltage and includes at least one magneto-resistor, and for shaping the measurement signal into an output signal of approximately rectangular shape. To simplify the circuit and reduce the number and size of the components and leads to a minimum, the current produced by the supply voltage is changed essentially in accordance with the changes of the AC component of the measurement signal by connecting a controllable impedance into the supply-voltage lead, the impedance being controlled by the measurement signal.