Hitachi, Ltd.

Takeshi Fukuhara

Hirotoshi Shirasu

Yuji Miura

Hidetaka Yamashita

Tatsumasa Oonuma

A bus connection detector circuit used for a switching network comprising a plurality of semiconductor switch elements of PNPN semiconductor four-layered structure, which are arranged in a matrix array and adapted to conduct upon the application of a potential thereacross. A plurality of diodes are connected at their one end to horizontal and vertical buses, respectively, and connected at their other end in common to one end of a voltage regulating diode for detection of the potential of the buses, and the other end of the voltage regulating diode is connected to a voltage level sensor, thus making up a single bus connection detector circuit, so that the connection of each bus can be detected by the single bus connection detector circuit.

Bus connection detector circuit for bus connection matrix circuit

A current supply system for terminal devices in which the line circuits are divided into groups in accordance with the line impedance thereof between an exchange or switching network and respective terminal devices or telephone sets, and a different voltage is applied to respective groups of line circuits which corresponds to the current matching the line impedance for the respective groups of line circuits.

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Fujisawa, Japan

Takeshi Fukuhara