Abstract: The charging apparatus for lead-acid-accumulators controls the charging current and the charging voltage above the gassing voltage level according to a linearly declining characteristic. The charging current and the charging voltage are converted to a current signal (50) and a voltage signal (60) which are normalized (70, 80) and combined (150) into an indicating signal (160) which is constant as long as the charging current and the charging voltage follow the linear characteristic. A regulating device (130, 140, 40) compares the indicating signal (160) to a reference signal (132) for correcting the charging current and the charging voltage. The current signal (50) and the voltage signal (60) are converted to the indicating signal (160) by means of a weighted summation. For performing the summation there is provided an operational amplifier circuit.

Abstract: The invention relates to apparatus for supplying an electric consumer with a high DC voltage which includes provisions for minimizing the danger and hazard of electrical shocks associated therewith. The apparatus includes a power circuit and a measuring control circuit which are separated by high ohmic resistors and an optocoupler.

Abstract: The invention relates to an ultrasonic measurement circuit of the type having an ultrasonic converter connected by a line to a transmission pulse generator. The circuit may have two transducers which operate alternately as a transmitter and a receiver and, in this case, the circuit also has a receiver amplifier. A resistor for preventing reflections is provided in the line between the pulse generator and the ultrasonic transducer which resistor is adapted to the wave resistance of the line. The pulse generator is shunted by a branch line having a switching device which becomes conductive at the end of the transmission impulse.

Abstract: Ultrasonic signals are transmitted alternately upstream and downstream in a fluent media. A reference signal timed to occur at the estimated time of arrival of the alternate signals is used to ascertain whether the actual signals arrive earlier or later than the reference signal. Control circuitry responsive to the early and late signals generates two signal levels associated with transmission direction which adjusts the time position of the reference signal until it coincides with the actual arrival times. One signal level is related to flow velocity. The other signal level is related to sound velocity in the fluent media.

Abstract: Several forms of multiplexing circuit are disclosed in which any selected one of a number of process responsive signal transmitters can be connected to a common measuring impedance by means of electronic switching devices individually associated with said transmitters. All transmitters are maintained energized at all times, whether or not they are addressed, to permit higher sampling speed.