GB1026684A - Automatic telephoning device - Google Patents

Abstract

1,026,684. Automatic exchange system. BROCKS ALARMS Ltd. June 12, 1963 [June 13, 1962], No. 22674/62. Heading H4K. A device for automatically dialling a telephone number on operation of an alarm circuit comprises a relay operable by the alarm circuit to make connections to the telephone line and to energize means for scanning and reproducing recorded signals, and transistor circuits responsive to the recorded signals for generating the dialling impulses. As shown, momentary short-circuiting of the alarm contacts AB energizes relay RL3 which locks, energizes gramophone motor M and makes connection to the telephone line. The recorded dialling signal comprises a continuous 2À5 kc/s. tone on which is superimposed pulses of 400 c/s. tone corresponding to the dialling impulses. The signals are reproduced by pickup arm PU and applied to transistor amplifiers TR1 and TR2. The 2À5 kc/s. tone is developed across the primary of transformer T1, rectified by D1 and operates transistor switch TR3 to energize relay RL1 and loop the line. The 400 c/s. tone is developed across R8, rectified by D4 and applied to transistor switch TR4 which energizes high-speed relay RL2 which follows the pulses and generates the dialling impulses by opening its contact RL2S. At the end of the number the 2À5 kc/s. tone is terminated and relay RL1 releases. Recorded speech is then applied to the line by transistor amplifier TR5 over transformer T2, diode D5 providing overload protection. When the message ends the normal pick-up switch opens, releasing RL3. The apparatus is manually reset by placing the pick-up in the first groove of the record. A narrow band-stop filter centred on 2À5 kc/s. is used during recording of the speech message to prevent unwanted operation of RL1. The gramophone record may be replaced by a magnetic tape or drum.