Abstract: A communication interface for connection to a communication apparatus provided with a balanced-type interface circuit includes a circuit for outputting a constant voltage approximately at the middle of the voltage level of transmitted data signals and is adapted to transmit to a balanced-type receiver contained in the communication apparatus a data signal as one input and the constant voltage from the constant-voltage circuit as another input.

Abstract: There is disclosed a new and useful taximeter which allows simple changes in tariff display conditions in various operating modes without any change or modification in circuit construction. The taximeter using a memory device removable from the taximeter body and containing lamp enabling and disabling information is capable of optionally setting tariff display conditions in respective ones of operating modes without reconstructing the circuit arrangement of the taximeter body.

Abstract: In an alarm system wherein a fault detection unit and a fault indication unit are spaced away from each other, long wires for detection signal transmission and for power supply, etc., are necessary. A fault indication driving circuit is provided within or adjacent to the fault indication unit, the bias voltage of the fault indication driving circuit being determined with the use of the detection signal transmission wire and the power supply wire in such a manner that the fault indication is enabled when one of the long wires is accidentally broken or placed in poor connection condition.