Abstract: To permit selective control of the voltage level of the on-board vehicle network as a function of battery voltage or exciter field control voltage of an automotive alternator, and continued operation of the regulator in spite of malfunction of control connections to the regulator, a voltage divide which supplies a voltage regulating element is formed with an additional tap thereon, the additional tap being connected to a current supply which supplies current to the voltage regulator to modify the voltge level of the tap supplying the control potential to the voltage regulator. The voltge regulator includes a controlled semiconductor switch which is selectively energized in accordance with voltage level at the main tap of the voltage divider with respect to a reference level.

Abstract: A STIFF POSITIVE FEEDBACK TO THE VOLTAGE REGULATOR TAP AT WHICH THE Zener diode in circuit with the control transistor of the regulator is called into play accelerates the switching operation at the operating thresholds of the regulator, while a negative feedback from the same regulator terminal, with inversion produced by a transistor, is applied to a second tap of the voltage divider farther from ground, where its effect is delayed by a capacitor that also serves to filter the command voltage applied to the regulator. The transistor that inverts the feedback acts as a controlled current source drawing current from the second voltage tap. The circuit is highly compatible with production by integrated circuit technology.