Abstract: To provide for essentially instantaneous stable operation of an electrical circuit, including an internal R/C feedback circuit, upon connection to an interruptible power supply source (+U.sub.S, G), the circuit includes an additional or auxiliary input terminal (14) which is connected to a series-capacitor network, including a series capacitor (C1, 19) serially connected between the additional terminal (14) and a power terminal of the power supply, and a shunt capacitor (C2, 18) connected between the additional terminal (14) and ground or chassis of the power supply; and wherein the capacity value relationships of the series and shunt capacitors are so selected with respect to the voltage of the power supply that the additional terminal will have a voltage corresponding to at least approximately the operating point (U.sub.V) impressed thereon upon connection of the power supply means.