GB409405A - Improvements in apparatus for interrupting carrier current - Google Patents

Abstract

409,405. Valve generating-circuits. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London, and BERRY, D. W., c /o General Electric Co., Stoke, Coventry. Nov. 4, 1932, No. 31169. [Class 40 (v).] In an interrupted carrier-wave generator wherein the interruptions are produced by applying sufficient negative bias to an oscillating valve, the valve is normally biassed by a condenser shunted by a leak resistance and the extra bias for interrupting the oscillations is obtained by disconnecting the leak resistance. This arrangement may be used for generating the special signals described in Specification 381,620. When contact 13 is closed manually or by a relay (not shown), relay 6 in the anode circuit of valve 1 operates and at 5 opens the circuit of leak resistance 4 whereupon negative potential builds up on the grid, anode current decreases, and relay falls back to repeat the cycle. When relay 6 pulls up it is held for a predetermined time by charging current for condenser 10, and when it falls back it remains unoperated for a further predetermined time since initial anode current will flow mainly from the condenser. By making grid condenser 3 relatively large or by permanently shunting it with a leak of suitable value, the carrier current is only partially interrupted. The signals are tapped off the coupling coil 15 and applied over an amplifying valve 17 to the transmission channel.