Patent GB-466348-A (GB)
Title: Improvements in burglar, fire and like alarm arrangements for use in telephone systems
IPC: H04M11/04
Filed: 1935-10-21
Abstract: 466,348. Fire, police, &c. systems; gramophones. ELECTRO-GARD'. Oct. 21, 1935, Nos. 29058 and 29059. Convention dates, Oct. 20, 1934 and Dec. 8, 1934. [Classes 40 (i) and 40 (ii)] [Also in Group XXXIX] In a police, fire, &c. alarm apparatus used in conjunction with a telephone system, the motor of the apparatus which is started automatically on occurrence of an alarm drives cam discs one of which connects the apparatus to line whereas another or others serve to transmit signals differentiating one kind of alarm (fire) from another (burglary) due to the operation of a relay in one alarm circuit. In automatic exchange systems the differentiating signals comprise numerical impulses for extending a connection to the appropriate station whereas in manual exchange systems the differentiating signals inform the operator. In the automatic system and the first of the manual exchange systems described, the location of the alarm is sent phonographically. Automatic exchange system, Fig. 1. Either kind of alarm closes circuit n2 to start motor m which drives cams c1, c2 and also c3, which rotates at “ the speed of c1, c2. When contact controlling member w engages portion u1 of the cam c3, impulse springs ql, q2 and gramophone pick-up h are connected across the line s at r1 and impulses are sent by cam c1 or c2 depending on which contact q1 or q2 is short circuited by relay n1 operated only in case of fire. After c3 has rotated through 90‹, contacts r2 shunt the impulse springs and another cam lowers the pick-up on to the record. After a complete revolution of c3, portion u3 lifts member w to break the telephone circuit and, at r<3>, to make a partial operating circuit for two-step relay n which operates contacts o, o1. Ultimately w descends to its normal position and one of the windings of n is shunted over r4, o1 to enable n to operate fully and open the motor circuit at o2, the relay being held over the alarm circuit n2. The tone arm is restored to its initial position. The circuit of relay n may include a contact opened by a cam for a period sufficient to enable the call to be repeated for a desired number of times. The contact controlling member w may also disconnect the telephone set from the line. Manual exchange systems. In one arrangement, Fig. 7 (not shown), cams c1, c2 are replaced by a single cam and the gramophone message is sent immediately the line has been looped. When the control cam c<3> has made # ths of a revolution a shunt on the impulse contacts of the single cam is removed and the contacts are connected to line if the relay n1 indicating a fire alarm has been operated so that the single cam transmits a Morse signal to the operator. The tone arm is restored during the sending of this signal. In another arrangement, Fig. 8, for local battery systems, cams c3, c<6> loop the line over a secondary of transformer T, the primary of which is fed with A.C. in parallel with the motor m so that the operator is called. After a quarter revolution of the shaft of cams c3, c6, the calling circuit is opened by c<1> and cam c3 closes a circuit from a low voltage secondary of T and one or other of contacts q1, q2 depending on the condition of relay n1 so that A.C. Morse signals denoting the nature of the alarm are sent to the operator. The operator stops the alarm apparatus by sending ringing current to operate A1 which locks up so that when cam c3 is about to complete one revolution A2 operates and opens the circuit of the motor. Control of gramophone Fig. 2. The tone arm g is lowered by levers e,f and rod i operated by a cam c4 and when the message has been reproduced, the tone arm is raised by the same mechanism a roller i<1> on rod i rolling down the incline arm of lever f to restore the tone arm.