Patent GB-270762-A (GB)
Title: Improvements in or relating to alarm circuit systems, particularly fire alarm signalling systems
IPC: H04M11/04
Filed: 1927-05-09
Abstract: 270,762. Snyders, G. C., Gordyn, C., Kamp, J. van de, and Maitland, C. E. A. May 10, 1926, [Convention date]. Fire, police, and like alarm systems.-The lines from individual call stations are led to district or distributing stations at which means common to several or all stations are provided for signalling the number of a calling line to a central station. In the system described, an impulse-sender ZG, common to all the lines AGSt111, AGSt222, &c., incoming to a district station VSt1, transmits code-impulses over the ieads a, b to an impulse relav BR1 at the central station, while a second impulse-sender (not shown) simultaneously transmits corresponding impulses over the leads c, d to a second relay BR2. Interference between simultaneous calls is prevented, and telephonic communication mav be established between 'the central station and the calling station. The district station has, individual to each calling station AGSt111, say, relays A111, B111, A<1>111, HR111, the relays V, 0, Y being common to a group of stations. The impulse-sender ZG comprises discs 1 - - 4, shown developed, having cams operating contacts such as 24, 29, 99. Normally, the line circuit of each call station AGSt111, say, is closed through relays A111, B111, Q111, the resistance of relay Q111 preventing the energization of relay A111. When a call is made, contact 1K closes the circuit of the telephone set N111, relay A111 energizing a common slow-release relay V. The line circuit is 'then opened momentarily at contact 2W, de-energizing relays A111, B111 to close the circuit of a self-locking relay A<1>111 which stores the call until the impulse-sender can deal with it. If the impulse-sender is in its normal position, relay A<1>111 energizes relay Y which starts the motor M, driving the impulse-sender ZG, the relay Y locking over contact 25 until the sender has nearly completed its cycle. The cam on disc 4 engages contacts 41, 40, 39 - - in succession until it reaches the contact of the calling line, whereupon the relay HR of that line energizes over its winding I and locks up over its winding II in series with a relay G which opens the circuits of the relays HR of all other lines so as to prevent interference. The first set of cams on the disc 1 closes contact 24 ten times, these impulses (hundreds) being repeated by relay 0 over the leads a, b, as described later until the cam on disc 3 reaches the contact 99 connected to battery by the relay HR of the calling line, whereupon relay Z opens the circuit of relay O and locks up until short-circuited at contact 98 shortly before the transmission of the next (tens) set of impulses. The tens and units impulses are transmitted similarly. At the end of the units impulses, a notch N in disc 2 opens contact 25 without closing contact 26, thereby ating Apparatus Co., Inc.). Aug. 23, 1926. sender remains in this position until the relay H1 or H2, energized from the central station, closes the circuit of relay Y to cause the motor M to restore the sender to normal. The leads a - - d to the central station are normally in a series circuit passing from the battery through a relay BR1, lead a, contact 4v, lead d, contact 12x, lead b, contact 3v, lead c, and relay BR2 to battery, the relay X not being energized by its differential windings I, II. When a station calls, the relay V reverses the current in one winding of relay X, thereby removing a shortcircuit around relay R, which establishes independent circuits for the impulse relays BR1, BR2 over the leads a, band c, d respectively. Relay BR1 records the impulses sent by relay O ot sender ZG, and relay BR2 the impulses sent by contact 1101 of the second sender not shown. Additional morse signalling can be effected over the leads a, b or c, d by short-circuiting a resistance in these leads. The leads a, b or c, d are connected by transformers M1 to the calling lines to permit telephony.