Abstract: A known oscillator with a 2-terminal coil without a tapping has only a limited dynamic controllability and apart from this is unsuitable for implementation in CMOS technology. The oscillator, first of all is extended by a current mirror. By the addition of the current mirror Q3, Q4 and additional power supply sources, one achieves a greater dynamic controllability and the suitability for implementing it in CMOS technology. By means of the excitation of the oscillating circuit with switched current sources Io, one achieves the proportionality of the oscillation amplitude to Rp and Io. In practice more complicated structures are used for switches and current sources. With this, an additional controllability of the oscillation amplitude independent of the damping of the oscillating circuit is obtained. The method is-used for distance measurement. The additional control of the oscillation amplitude is utilized for the correction of the manufacturing tolerances and of the temperature-dependence.

Abstract: The invention relates to a method for the measurement of the molar mass of a gas or gas mixture and an apparatus for the performance of the method. The gas or gas mixture to be investigated is passed through at least one holder, on which at least one sonic or ultrasonic transmit-receive cell is arranged defining a baseline and preferably arranged obliquely to the axis of the tube. The sonic or ultrasonic transmit-receive elements radiate a pulsed sonic signal, which measures the transit times of the sonic pulses along the baseline. Using a temperature probe for instance the variations in gas temperature along the at least one sonic transmission path is determined. From the transit time of the sonic pulses and the measured or assumed temperature the molar mass is found. The apparatus in accordance with the invention may be employed with advantage in pulmonary function diagnostics.

Abstract: The invention relates to an apparatus for measuring the parameters of respiratory gases comprising a respiratory tube, ultrasonic sensors and pre-amplifier electronic circuitry arranged in a separate housing. In order to prevent dangerous cross infections between patients following repeated utilization of the such measuring apparatus the ultrasonic sensors are permanently integrated in the respiratory tube so that they constitute a single part therewith and in that at least the respiratory tube together with the integrated ultrasonic sensors is designed in the form of an interchangeable part for use once only.

Abstract: To obtain optical one-way transmission of bioelectrical potential differences between electrodes placed on a patient and the evaluation apparatus, one of the electrodes placed on the patient is designated as the reference electrode. The potentials of all the other electrodes are referred to this electrode, and the signals derived from the potential differences so obtained are amplified, multiplexed, converted analog/digital and transmitted in coded form. At least one of the potential differences recorded by the evaluation apparatus is derived from the difference between two transmitted signals. The number of signals transmitted can thus be less than the number of potential differences recorded. This process is particularly useful for transmitting electrocardiogram signals (ECG signals) to an ECG apparatus which produces twelve standard derivatives. The optical transmission can also be performed by an optical fibre.

Abstract: A pulse-width modulator circuit includes a pulse-width modulator which has an input for a low-frequency modulation signal and an input for a carrier signal, a carrier signal generator which has an output connected to the carrier signal input of the pulse-width modulator for providing a carrier frequency, a buffer stage postcoupled to the pulse-width modulator, an output filter postcoupled to the pulse-width modulator, including a relatively narrow-band resonant circuit for damping the carrier frequency, and a regulating device forming a feedback path between the resonant circuit and the carrier signal generator for maintaining the carrier frequency substantially at the resonance frequency of the resonant circuit.

Abstract: A method of, and circuit for, producing measuring pulses in a particle analyzer for the analysis of particles suspended in a liquid, especially blood cells, comprising a conductivity or measuring cell, whose impedance between two terminals of the conductivity cell changes upon passage of a particle through such conductivity cell. A controllable current supply powers the conductivity cell with a current regulated to maintain a reference value corresponding to a control value. A receiver functioning as a high-pass filter and having high input impedance serves for the essentially currentless removal of a potential between the terminals of the conductivity cell and for forming a receiver signal corresponding to such components of such potential whose frequency is above a threshold or cut-off frequency corresponding to the high-pass filter. The control value is formed from the sum of a predetermined reference value and the received signal.