Abstract: A printed circuit board includes an oscillator and a modulator. The oscillator includes a first printed inductor and a capacitive diode which are printed on one side of the printed circuit board. The modulator includes a second printed inductor coupled to the first printed inductor and printed on the same side of the printed circuit board as the oscillator. A conductive surface at a reference potential is arranged the other side of the printed circuit board and in the vicinity of the oscillator and the modulator and electrically coupled to the oscillator and the modulator using conductive through holes.

Abstract: A circuit arrangement for switching-through (transit switching) of RF-signals is provided. The signals from several RF-signal sources are switched via controlled diode paths wherein capacitance diodes are used for achieving a high value of decoupling between sources in the unenergized state.

Abstract: A circuit for generating a cut-off voltage for the switching diodes in a high frequency filter by rectifying the output signal of an oscillator includes a first diode which has a low threshold voltage and which rectifies the output signal to apply the cut-off voltage to the switching diodes in a first mode of operation. A second diode, having a low resistance, is parallel to the first diode and by-passes the first diode in a second mode of operation.

Abstract: A circuit arrangement for distributing an antenna signal to input terminals of two appliances. One of these appliances is connected to a variable frequency modulator. An attenuating filter stage is connected between a pre-amplifier and the input of the appliance that is connected to the modulator. The pre-amplifier receives and amplifies the antenna signal. The attenuating filter stage is a frequency trap which has a trapping frequency that is identical to the modulator frequency and is synchronized with tuning of the modulator frequency. The attenuating filter stage, furthermore, is always exactly tuned to the frequency of the modulator and has a tuned frequency that is always aligned in parallel to the frequency of an oscillator in the modulator, so that modulation is not present.

Abstract: A mixer circuit with a conventional very high frequency circuit for the reception of color television bands I and III, which is connected dependent on the band and which is provided with an NPN transistor. The NPN transistor operates via a collector resistor onto a two circuit band filter. Moire interferences in the band I region expanded for CATV are avoided by having the mixer current used to 0.3 to 0.6 mA via a counter coupling resistor disposed between base and hot end of the resistor 4. Thus the self-interference in band I is reduced by a value of about 60 dB. In case of band III operation the corresponding switching voltage is fed via a series connection of a diode 6 and a resistor 5 to the base and thus the base level is lifted up to higher mixing current, since in band III self-interferences cannot occur in the case of the presence of signals.

Abstract: Apparatus for ascertaining the quantity of ozone in water and for admitting additional ozone when the ascertained quantity is insufficient has two spaced-apart electrodes which consist of an alloy having gold as the predominant constituent thereof and which can be immersed into a body of water. Each electrode is connected with a discrete voltage source by way of a discrete resistor whose resistance is substantially greater than the resistance between the electrodes when the electrodes are immersed in water. The potential difference between the electrodes is measured by a differential amplifier whose output transmits a voltage signal having an intensity proportional to the percentage of ozone in the body of water into which the electrodes are immersed.