Abstract: A circuit arrangement for adjusting the amplitude of a signal includes first and second differential transistor-amplifiers. One of said amplifiers is arranged to receive the signal via its main-current-path input and the other amplifier is arranged to receive a direct current supply corresponding to the d.c. component of the signal. The amplitude of the signal is adjustable by means of a control voltage applied to the cross-coupled control terminals of the differential amplifiers, and the amplitude adjusted signal is available on two cross-coupled main-current path outputs of the amplifier. The circuit can be energized with low supply voltages and at the same time can handle large amplitudes of the signal to be adjusted by means of a current summing circuit in which an output direct current corresponding to the direct current supplied is subtracted from the amplitude adjusted signal.

Abstract: In a circuit arrangement for optionally connecting the outputs of a plurality of signal sources which produce signals consisting of d.c. and a.c. components to an input of a signal sink, an interference-free switching is accomplished by providing that all the signals supplied by the signal sources from their outputs.

Abstract: A circuit for level adaptation between an I.sup.2 L circuit and a preceding combinatory logic circuit. The input current for the I.sup.2 L circuit is supplied by a direct current source which is connected to several switches which are controlled by the level on the output of the combinatory logic circuit, at least one of the outputs thereof being connected to an input of the I.sup.2 L circuit via a current mirror.

Abstract: Circuit arrangement for receiving two modulating signals, more specifically for television, particularly for the transmission of stereo signals or dual channel independent sound signals, each of the two modulating signal being conveyed through respective variable amplifiers, the gain of the amplifiers being adjustable in the opposite current directions for an optimum dematrixing of the stereo signal and being switchable by a factor of 2 for the reception of dual channel independent sound signals.

Abstract: The invention relates to a circuit for use in a receiver which can receive two-tone/stereo signals. This circuit is intended to make a choice between mono or stereo reproduction of signal A or of signal B and vice versa. The circuit comprises two bistable multivibrator circuits which are controlled by a common, user-operable switch and by characteristic signals which are derived from the characteristic frequencies relevant to the different types of programs. The control is such that when the switch is operated only one bistable multivibrator circuit can be changed over (namely the bistable multivibrator circuit associated with the relevant characteristic frequency received.) A logic circuit which is controlled by the bistable multivibrator circuit as well as by the characteristic signals operates a change-over switch for switching to the desired reproduction.