GB434634A - Improvements in or relating to telephone systems adapted for recording and reproducing the transmissions - Google Patents

Abstract

434,634. Substation equipment. JAEGER, O., 70, Mythenquai, Zurich, Switzerland. Nov. 26,1934, No. 33993. [Class 40 (iv)] [See also Group XXXVIII] A telephone substation is associated with an amplifier and with phonographic apparatus of slowrunning telegraphone type by a switching arrangement which enables the system to be used at will, (1) as a loud-speaking telephone system, (2) as a system in which conversations are recorded, (3) as a local recording system, (4) as a system in which an automatic reply signal is given by a disc gramophone in the subscriber's absence and an incoming message is recorded, (5) as a reproducing system. Telegraphone driving arrangements. The spools 22, 23, which are housed in a casing 42, are mounted on shafts 43 having perforated collars 44 engaged by pins 45 on the spools. On the operation of a clutch magnet 46 a plate 49 carrying pins 49a and mounted to slide but not to rotate on shaft 43 is forced into engagement with a disc 50 rotatably mounted on shaft 43 and driven by the motor 27. Geared to one of the driving shafts 43 is a cam 59 which rocks the pick-up device 26 to ensure even winding of the magnetized wire. Also geared to the same shaft 43 is a screwed shaft 64 mounted on the spool casing and carrying a nut 65. As a spool unwinds the nut travels along the shaft and by means of a Bowden wire secured to a spring drum moves an indicator (not shown). At the end of its travel the nut releases the operated clutch magnet. When the casing is removed a stud 22b, Fig. 9, secured to the spool by a spring enters a hole in the casing to lock the spool. As shown, the clutches control the driving of the wire in either direction by a single motor, but separate driving motors may be employed. Construction of recording device. The recording device, Fig. 6, comprises a pair of pre-magnetizing magnets 71 and a pair of recording magnets 70. The poles of each pair are relatively displaced by an amount about equal to the width of the magnet core and project through a pair of glass plates 26<a> to which they are secured by putty and between which the wire F travels. The ends of the poles are flush with the surface of the glass so that wear is prevented although the poles and wire are in contact. Guide plates 26b are provided in pairs at each end of the device. In an alternative construction the poles may be spring-urged towards the wire. Operation as loud-speaking telephone system. Key 5 is thrown to the right to operate springs 82, when a call is received or is to be originated, key 6 remaining in the mid-position. As a result, the bell circuit is broken, the valve filaments are lit and the a-wire of the line connected to the end a of the primary of transformer 86. Microphone 75 is connected across the points a, b on the transformer primary, the lower end c being permanently connected to the b-wire. The transformer secondary is connected to the input transformer 92 of the pentode amplifier, the output of which is connected to the loud-speaker 2. Acoustic back coupling is prevented by an adjustable resistance 87. Recording during conversation. Key 6 is thrown to the right in addition to key 5. Clutch magnet 25 is operated, switches on the driving motor 27 and lights the pilot lamp 8. The pre-magnetizing magnets 71 of the recorder are energized and the left-hand portion of the potentiometer resistance 67 across the recording magnets 70 is inserted between the output terminal of the amplifier and the loud-speaker, resistance 88 being cut out so that the volume of sound from the loud-speaker remains un- I altered. If the telegraphone wire runs out, the nut 65 on shaft 64 operates the inner springs of the set 29 to light the warning lamp 9 and shortly afterwards the outer springs release the clutch magnet and so switch off the motor. Reproducing recorded message. Key 6 is restored to the mid-position and switch 76 is operated to energize clutch magnet 24 which switches on the motor, lights lamp 8 and disconnects one end of potentiometer 67. The telegraphone wire is thus wound backwards and when the nut 65 reaches the end of its travel, springs 28 release the clutch magnet which switches off the motor. Key 5 is then thrown to the left to light the amplifier filaments, operate clutch magnet 25 and connect the recorder magnets to the amplifier input. The output is connected to the loud-speaker. Cancelling records. Push button 77 enables the pre-magnetizing coils 71 to be energized to cancel any record while the wire is being driven backwards. In recording any message remaining on the wire is cancelled by these magnets just before the new record is made. Recording messages in the absence of the subscriber. Key 5 is left in the mid-position and key 6 thrown to the right. With the keys in this position no current passes normally, but when a call arrives, relay 34, which is bridged across the line, responds to the ringing current, energizes 35 and connects the current supply to the driving magnet of the reply gramophone 32. 35 locks up, cuts off 34, prepares the connection of the potentiometer resistance 67 across the line and energizes clutch magnet 25. Off-normal springs controlled by the reply gramophone keep it running, connect the pick-up 33 across the line and, on restoring to normal, stop the motor and complete the connection of 67 to the line in place of the pick-up 33. The message is thus recorded without amplification. The inductive kick when the calling party hangs up momentarily operates 36 (which in series with condenser 69 is across the line), to unlock 35. Recording local dictation. Key 5 is left in the mid-position and key 6 is thrown to the left. Clutch magnet 25 is operated, current is fed to the amplifier filaments, microphone 75 is connected to the input transformer of the amplifier in series with the filament source and the output of the amplifier is connected to the recording magnets through resistances 88, 89.