Patent GB-399519-A (GB)
Title: Improvements relating to direction control switching arrangements for electrical signalling systems
IPC: H04L25/04
Filed: 1932-04-06
Abstract: 399,519. Two-way transmission. ELECTRICAL RESEARCH PRODUCTS, Inc., 195, Broadway, New York, U.S.A.- (Assignees of Knoop, W. A.; 36, South St. Paul Road, Hempstead, New York, U.S.A.) April 6, 1932, No. 9921. Convention date, April 28, 1931. [Class 40 (iv).] In a two-way telegraph repeater, the direction of transmission is controlled by a vibrating relay, whose armature, in the absence of signals, alternately prepares the circuit for repeating in one direction or the other but as long as signals are received from one station maintains the circuit for repeating these signals to the other station. Repeater utilizing thermionic valves. The switch 16 is controlled by solenoids 17, 18 energized by a battery 20 according to the position of a relay 19, which is energized by the plate currents from valves 21, 22. Signals from a cable 11 pass over contacts B to a shaping amplifier 13 with two output circuits 25, 27. The output 25 is connected to a retransmitter 15 feeding cable 12 over contacts C, while the negative output 27 is impressed on a condenser 28 and biases valve 21 to a negative valve lower than that of valve 22 which is biased by battery 29 over contacts D. The plate current 'of valve 22 exceeds that of valve 21 and the relay 19 is maintained in a position for energizing solenoid 17. Should signals cease, the voltage on condenser 28 leaks away through resistance 31, and the plate current in valve 21 rises and reverses the relay 19 actuating the switch to close contact A, open contact B and reverse the connections between cables 11, 12. Should signals arrive from cable 12, the repeater will be maintained in a position for repeating by the lower negative bias on valve 22 over conductor 35 and condenser 36, but on cessation of signals, the bias on valve 22 leaks away over resistance 37 and the relay. 19 is actuated to reverse connections. The period of actuation of relay 19 when no signals are received is preferably almost equal to that of one revolution of the rotary distributor at the transmitting and receiving stations. Repeater utilizing relays. In Fig. 2, the circuit arrangement of cables 11, 12, switch 16, shaping amplifiers 13, 14 and retransmitter 15 is identical with Fig. 1. When no signals are received, the winding P of the relay 19<1> is energized in one direction or the other according to whether contacts A or D are closed and energizes solenoid 17 or 18 from a battery 20 to actuate switch 16 and reverse contacts A, D. When signals are received from cable 11, the alternating output circuit 27<1> of the shaping amplifier 13 actuates relay 21<1> to alternately energize the windings Q, R, of the relay 19<1> from batteries 23<1>, 23<11> and maintain the switch 16 in a position for repeating. The condenser 38 in the circuit of the windings Q, R, limits the current flow so that when signals cease and relay 21<1> ceases oscillating, the current flow on the winding Q or R ceases, and the relay 19<1> is once more actuated by the current in the winding P. Should signals arrive from cable 12, the relay 22<1> is actuated to energize windings S or T of the relay 19<1> and maintain the switch 16 in a position for repeating.