Abstract: A circuit capable of reducing power consumed by all of the signal lights at a street intersection is presented. The circuit comprises activating switching means which activate the circuit. The circuit further includes timing current interruption means which are turned on by the activating means. The timing current interruption means inhibit the 24 volt, low voltage supply to the load switches of the selected signal lights thereby preventing the power normally supplied to the signal lights from being supplied to the signal lights while the low voltage supply is inhibited. A preferred mode of operation inhibits alternate cycles of the AC power so that only 30 or every other of the 60 cycles of AC power normally transmitted to the traffic signal light each second are actually transmitted to the traffic signal light.

Abstract: A method of testing a plurality of repeaters arrayed along a transmission line of a pulse code modulation system, and of locating any faulty repeaters, both testing and fault location being performed automatically. Pulse train groups, each containing a frequency component corresponding to a supervisory signal frequency of one of the repeaters, are successively applied from one terminal of the transmission line. Each pulse train group comprises a plurality of subgroup pulse trains, each of which contains the supervisory frequency component of the pulse train group to which it belongs, with the density of a pulse train in successive subgroups being successively increased. Any faulty repeater is located by determining the pulse train density at which a supervisory signal produced by the repeater fails to increase by a predetermined amount for a known change in pulse train density.

Abstract: In a teleprinter private branch exchange having a communications unit, to which teleprinter terminals are connected, a central unit and a storage unit, the load due to connections between the individual units on a bus connecting the individual units together is kept as low as possible. For this purpose, the individual units are connected to the bus through the processing systems such that the processing unit of the central unit controls the connection of the processing units of the other two units using the bus for just one signal transmission. It is also provided that the processing unit of the central unit also triggers the execution of the procedures to be executed in the communications unit and supplies the addresses of those storage areas in the storage unit in which associated signals are to be stored or are stored.