Abstract: A method of measuring under running conditions operation parameters of an interface circuit and a telephone subscriber line connected to it, said interface circuit comprising a first integrated circuit operating on a high voltage with outputs connected to the line and second outputs on which transverse and longitudinal current values of the line are respectively present in normal operation, and a second integrated circuit operating on a low voltage between the first circuit and a telephone exchange, comprises the steps of: switching the outputs across an impedance of a predetermined value, and measuring through the first circuit the values of the currents present on the second outputs; switching said outputs back to across the line leads, and measuring through the first circuit the values of the transverse and longitudinal line current values; performing, for each measurement through the second circuit, a digital encoding of the measured values and transmitting such encoded values to the telephone exchange.

Abstract: A circuit assembly which includes an interface circuit between a subscriber line and exchange devices of the kind with two amplifiers connected in a bridge configuration between the battery terminals and having a means of detecting the output currents; a supply circuit which includes the exchange battery and a ring generator; a switch-over means for putting the line through the interface circuit or the supply circuit; two bridge resistors which are in series with the line when the latter is connected to the supply circuit and of which one is connected permanently between one of the line terminals and the output of one of the amplifiers, which output is substantially at the potential of one of the battery poles; an additional resistor, having a much higher resistive value than that of the bridge resistors and being connected between the other of the line terminals and the output of the other of the amplifiers; and a processing means within the interface circuit, which includes said detecting means and is effec

Abstract: An integrated circuit bandgap voltage reference, in which the regulated voltage is equal to the sum of a first transistor's base-emitter voltage plus a voltage which is proportional to the difference between the base-emitter voltages of two transistors operating at different current densities, PLUS an additional voltage which is equal to the base-emitter drop of an additional transistor. The additional transistor is connected to an emitter resistor which ensures that variations in resistor values will cause the base-emitter drop of the additional transistor to vary oppositely to the base-emitter drop of the first transistor. The resulting voltage reference circuit has high stability and low power consumption.