Input circuit for a signalling system which cyclically scans a plurality of signalling stations under counter control

Claim 1

An input circuit for a signalling system which cyclically scans a plurality of signalling stations under the control of a pulse generator via a counter, each of the signalling stations having a magnetic core having a control winding and a rectangular magnetizing characteristic for storing received signals, said input circuit comprising a DC voltage source having a positive polarity terminal and a negative polarity terminal; a plurality of changeover switches each at a corresponding one of the signalling stations and each having a switch arm having a fixed electrical terminal at one end thereof, a first contact terminal electrically connected to the positive polarity terminal of said DC voltage source and a second contact terminal electrically connected to the negative polarity terminal of said DC voltage source; a bus bar for applying a potential between the potentials of the terminals of said DC voltage source; a counter having an input and outputs; a pulse generator connected to the input of said counter and controlling the operation of said counter; decoding means having inputs coupled to the outputs of said counter, said decoding means having outputs; and a plurality of transistor circuits each at a corresponding one of the signalling stations, each of said transistor circuits comprising a PNP type transistor and an NPN type transistor connected in parallel with each other and connected to the fixed terminal of the switch arm of the corresponding one of said changeover switches, each of said transistor circuits being electrically connected to said bus bar via the control winding of the corresponding one of said magnetic cores, each of the transistors of each of the transistor circuits having a base electrode connected to that of the other of the transistors and coupled to an output of said decoding means.