GB470654A - Improvements relating to telegraph signalling apparatus - Google Patents

Abstract

470,654. Code telegraphy; valve relaying circuits. CABLE & WIRELESS, Ltd., and HUMBY, A. M. March 19, 1936, No. 8282. [Classes 40 (iii) and 40 (v)] A regenerative telegraph repeater comprises a " flip-flop " system, having two positions of equilibrium corresponding respectively to the transmission of outgoing marking and spacing signals and consisting of two thermionic valves each having its anode connected to the grid of the other, the system being placed under the control of the incoming signals only for a fraction of each signal at which the marking or spacing condition is definite by a relay device controlled periodically at a frequency corresponding to the shortest marking or spacing condition. As shown, the " flip-flop " system consists of two valves 1, 2 each having its anode connected through a resistance to the grid of the other, the cathodes being kept at a positive potential by connection to a resistance 3, and the grids being connected to ground through grid-leak resistances 6, 7. The relay device consists of a valve 22 of which the grid is connected to a multi-vibrator circuit comprising valves 10, 11, each having its grid connected to the anode of the other through a condenser and there being separate and common resistances in the anode and grid circuits. At such times as the valve is conducting it connects the grid of one or other of the valves 1, 2 to ground so that the valve if operative ceases to pass current, the other valve becomes operative, and the corresponding winding of relay 8 is energized. Suitable values are given for the various resistances, in the circuit: The frequency of the multi-vibrator circuit is synchronized with the signals by a connection through a variable condenser 28. The relay valve 22 may be replaced by an electromagnetic relay controlled over a single winding or, if polarized, over two windings by the multivibrator.