GB340583A - Improvements in printing telegraph apparatus - Google Patents

Abstract

340,583. Type-printing telegraphy. STANDARD TELEPHONES & CABLES, Ltd., and McWHIRTER, E. M. S., Columbia House, Aldwych, London. Sept. 27, 1929, No. 29296. [Class 40 (iii).] A keyboard transmitter for printing telegraph apparatus comprises a key for each signal, contacts being operated selectively by the keys to connect simultaneously to the line a code combination of alternating currents of different frequencies taken one or more at a time representing the signal to be transmitted. The transmitter may act as a receiver, each key having a solenoid S, which is selectively energized [Fig. 3 (not shown)]. The transmitting contacts are operated by a key lever K, Fig. 1, operating typewriter mechanism, and having an insulating wedge W, cut so as to operate six contact springs Pi .. P6, P1 making contact last. The contacts P2 .. P6 actuate five relays R1 .. R5, Fig. 2, which connect to the line a combination from the five frequencies ; contact P1 actuates a slow-acting relay R6 which breaks the circuit of relays R1 .. R5. The two stations, A, B, each has a send-receive switch SW, that for A being in the transmitting, and for B in the receiving position. Relays V1 .. V5, tuned to the respective frequencies, are connected across the line and actuate relays X1.. X5, the contacts A .. K of which select the solenoid to be operated, in accordance with Fig. 3 (not shown), thus printing the required letter. The frequencies, which should be within voice frequency range so that long telephone lines may be used, may be produced by commutators ; in this case relays R1 .. R5 may be removed, contacts P2 .. P6 connecting the frequency circuits directly to the line. Also, relays V1 .. V5 may be connected to the line through the " receive " position of SW, their respective contacts actuating the selector circuits of Fig. 3, thus eliminating relays X, .. X5.