Abstract: Semiconductor circuits for the automatic generation of tone sequences of different tones. A bistable switch having a control input activated by start signal controls a voltage stabilizing circuit which in turn controls an RC-oscillator. Several frequency dividers are driven by the oscillator for producing divider outputs as tone signal outputs furnishing individual tone frequencies corresponding to the tone sequences to be produced. A general cycle control has inputs controlled by the first divider output. Modulator modules driven by the cycle control and by the tone signal outputs, are connected to the digital-to-analog converters which produce tone signal outputs that correspond to the individual tone frequencies. The digital-to-analog converters have outputs that are jointly connected to an electro-acoustic transducer, such as a loudspeaker.

Abstract: Monolithically integrable logic circuit having at least one NAND function and a Darlington stage serving as the signal output of the circuit, including a differential amplifier having its non-inverted output connected to the input of the Darlington stage, the differential amplifier including at least two identical input transistors with control electrodes which form the signal inputs of the circuit and a reference transistor which is identical to the input transistors, the reference transistor having one of its current carrying electrodes connected to the same current carrying electrodes of the input transistors, a current source connected to the connection of the input and reference transistor electrodes, and a switch-over system including transistors and diodes for switching the input transistors to different threshold voltage values, the switch-over system being connected to the control electrode of the reference transistor.

Abstract: A process for the production of a locally high inverse current amplification in a preferably double diffused or implanted inversely operated transistor which includes forming a low doped epitaxial layer of one conductivity type on a high doped semiconductor substrate of the same conductivity type, forming a high doped buried region by ion implantation in the epitaxial layer beneath the zone provided for the collector, forming a low doped second region of the opposite conductivity type, above said first region which covers an area substantially wider than said first region and forming a third high doped region in the surface of the epitaxial layer spaced above said first region and having an area smaller than said first region, the first region forming the emitter, the second region forming the base and the third region forming the collector, the second region extending to the surface surrounding said third region and partially surrounding the first region.

Abstract: A protective circuit for short circuit and overload protection of a power circuit, particularly integrated power circuits, in which the input of the final stage of such power circuit is controlled over an AND gate having a second input connected to the output of a flip-flop circuit. The latter is set by a pulse generator to close the input circuit of the final stage and in case of an overload the flip-flop is reset in response to an overload sensor, whereby the AND gate is blocked, and the final stage input circuit opened, during the pulse intervals as long as such overload exists.