US1407046A - Telephone apparatus - Google Patents

Description

J. F. TOOMEY.

TELEPHONE APPARATUS.

APPLICATION FILED MAY I6, 1919.

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KNVENTOYR Jliolmy BY ATTORNEY Patented Feb. 21, 19 22.

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xi '1 Y 1. s I 6 a is o r. 3 me i. i h as" i i his o 358313.221, N. "51".. AfifiIGNGR 'lO AMERICAN TEIiEIPEZGEilE AND 46 one 9 s Application filed. na 1e,

the receiving on telephone circuits and the arrangements are intended particularly to be used at substations where the subscribers are unable to hear properly with the usual substation apparatusor Where other circumstances make it especially desirable to nu p is required.

prove receiving.

in general an improvement in receiving may be ei fected by connecting a telephone repeater amplifier in the receiving circuit at the substation, so arranged that it will amplify the voice currents in the receiving circuit. Where an arrangement of this kind is employed With ordinary types of telephone substations, the amplified currents in the receiver are of suiiicicnt magnitude under certain conditions to aidectthediaphragm of the transmitter, thereby creating a condition known. as singing. This feature. in addition to beingob iectionable to the subscriber, practically makes the arrangement inoperative if any appreciable amplification Furthermore with such an aren enient the currents in the receiver are of such magnitude that the subscriber could not speak directly into the transmitter mouthpiece without making the receiver currents objectionably loud. Accordingly to prevent such diiiiculties the substation cmlodicd in the. arrangements of this invention'includes a side tone reduction coil of the type illustrated in the U. 5i. Patent No.- lfil/L'T'l granted to G. A. Campbell reference being had to Fig. 1;. of said patent. Due to the amplification oi the receiver current some means is desirable in this arrangement to prevent objectionable and possibly dangerous clicks in the receiver due to static discharges on the line or an accidental connection of ringing current to the circuit whi'ie the subscriber has he receiver to his ear. in the arrangements of this invention.

AEPARATUS.

Specification of Letters Eateut. Pgieniagqi 231 @9252 1919. Serial No. 297,452.

this is accomplished by including therein a bridge or shunt across the input circuit of the repeater amplifier, the bridge including an element such as carhorundurn which has the property or decreasing in resistance When subjected to a sudden lllCl'afiSQ in voltage on the line. Accordingly a sudden in-. crease of voltage on the telephone circuit would cause the bridge to operate-as a shunt for the, current. T he invention furthermore includes means whereby the repeater amplh iier may be switched in and out of the receiving circuit and its eflicienc'y regulated by the operator. Supervisory apparatus inlay also be associated with the arrangements of the invention. Other and further features of the invention will be more clear from the detailed description of the operation of the invention:

'- In the drawing is illustrated a circuitdiagram of a preferred form of the invention.

While the arrangements or the invention have been specifically illustrated as associated with a private branch exchange. it is understood that it is capable of embodiment in many other forms of circuits. station 1 is illustrated which includes a transmitter '2, a receiver 3, and the windings i, 5 and 6 so arranged as to substantially reduce and prevent side tone disturbances, siniiiar arrangements being illustrated, in the U. S. Patent No. 1.254.116 to G. A. Campbell. The substation 1 is connected to the jack J at the switchboard of the private branch exchange operator. A. jack J is also provided for testing the current iiow over the circuit. For this purpose a plug (not shown) would be provided which might be connected to an amulet-er and by this means the amount of current flowing through the repeater circuit might bodetermincd for testing purposes. Associated with the receiver circuit is the repeater amplifier 12, which is of the type illustrated in the U. S. patents No. 1,156.636; and No. 1,159,603 to H. E. Shreeve. in repeater 12 the repeater button is'illustrated as 13. the magnetizing winding is 16 and is connected to the retardationccil 17. the compensating;winding is 14*. and i5 is the receiving winding. Located at the switchboard of the private branch exchange are the keys K K and K lVhen the key K is operated the operators supervisorv' apparatus associated with corn ductors 28 may be connected to the receiver A. Sub- &

circuit. When the keys K, or K are operated the repeater 12 is connected to the receiver circuit and rendered operative. The

key K furthermore controls the relay 22 and means for regulating the gain of the repeater. Bridged across the input path of the repeater is'the shunt 10 including carborundum element which will decrease in resistance when subjected to an increase in voltage. Any sudden increase of voltage on the telephone circuit accordingly will reduce the res1stance of the shunt path 10 and the increased currents transmitted to the receiver circuit will be shunted through the path 10. By this means objectionable and possibly dangerous clicks in the receiver due to static discharges on the line or other end den increase of current thereover are prevented.

The invention may now be more fully understood from the following description of its operation.

If a connection is desired with the subtation l, the operator at. the private branch exchange will insert the plug of her cord circuit or of the calling line into the jack J. The connection will then be completed to the receiver of the substation as follows: from the tip contact of jack J, conductor 8, winding 4, contact 34, conductors 35, 36, 87 and 38, contact 70, to the receiver 3,-and also from the ring contact of jack J over conductor 7, winding 6, conductors 39, 4:0 and 4;]. to the receiver 3. If the operator desires to monitor or supervise such a connec tion, the key K will be operated and the following circuit closed: from ground, contact of key K conductor i2, winding of relay 27, to battery. The closing of this circuit will operate relay 27 and connect the conductors 28 leadin to the operators telephone set to the conductors 40 and 41 of the above traced circuit. If it is desired to include in the connection therep'eater apparatus 12 either the key K or the key K may be thrown. If the key K is thrown, the following circuit will be closed: from round, contact of jack J, upper contact of rey K conductor 42, winding oi relay 9, conductor 13, winding of relay 26, conductor 44, to battery 32, and ground. At the same time a circuit will be closed from ground, contact of jack J, upper contact of key K conductor 45, winding of relay 29, conductor 46, to battery 32, and ground. The closing of these two circuits will operate the relays 9, 26 and 29. Theoperation of relay 29 will apply battery to the repeater apparatus 12 over the following circuit: from ground, battery 31, contact of jack 5,, conductor 47, contact and armature of relay 29, filament of ballast lamp 30, over conductor 21, to the repeater apparatus. The closing of this circuit will render the repeater apparatus 12 in a condition for opemes oration. The operation of relay 9 will connect the input circuit of repeater 12 to the induction coil of substation 1 and the op-' eration otrelay 26 will connect the output circuit of repeater 12 to the receiver of substation 1. Accordingly, the current comingin over conductors 7 and 8 to the substation will now be transmitted over con ductors 36 and 39 and over contacts and armatures of relay .9 through the left hand winding of transformer 11. This current will then be transmitted over conductors 18 and 19 to the repeater 12 and will be transmitted in amplified form therefrom over conductors 20 and 21. This current will be transmitted from conductor 21 through the left hand winding of transformer 23 as follows: from. conductor 21, right hand normal contact of relay 22, conductor a8, series resistance 25, conductor 49, left hand windings of transformer 23, conductor 50, to conductor 20. Bridged across this circuit is the shunt resistance 24. The shunt resistance 2e and the series, resistance 25 are so proportioned as to regulate the gain of the repeater to a desired degree. The amplified current will then be transmitted through the transformer 23 and over condoctors 52 and 53, armatures and contacts of relay 2G, and over conductors 54 and 41, to the receiver 3. If the operator upon supervising on a connection completed as described ascertains that the repeater is not giving thedesired degree of amplification, the repeater may be adjusted so as to give a greater gain. This is accomplished by throwing the key K The throwing of key K, closes the following circuit from ground, contact of jack J, lower contact ofkey K conductor 55, winding relay .22, to battery and ground. The closing of this circuit will operate the relay 22. At the same time ground will be applied from the upper contact of key K, to conductor 42 and the previously traced circuit through relays 9 and 26 will be held closed. The operation of relay 22 will disconnect the shunt resistance 24 and the series resistance 25 from the output circuit of repeater 12 and the output circuit of repeater 12 will now be completed as follows: from conduc- -.tor 21, right hand make contact and arma-;

ture of relay 22, left hand windings of transformer 23, conductor 50, to conductor 20. The removal of these resistance elements from the output circuit of the repeater will increase the volunu: of sound in the receiver 3-. It is pointed out that the repeater ape paratus cannot be conditioned for operation or connected to the substation by the o eration of either the key K, or the key a until a plug such as the plug of the operator: cord circuit or of the calling line has been inserted in the jack J and ground applied to the upper contact thereof. This arrangement serves as a safeguard to prevent the arrangements from functioning until a con nection has been made with the substation.

While the invention has been disclosed as embodied in certain specific arrangements which have been deemed desirable, it is understood that it is capable of embodiment in many and widely varied forms without departing from the spirit of the invention as defined in the appended claims.

What is claimed is:

1. In a telephone system, a substation including a side tone reduction coil and a receiver circuit, an amplifier associated with said substation, a plurality of switching means, means controlled by each of said switching means for including said amplifier in said receiver circuit, means controlled by each of said switchingameans for rendering said amplifier operative, and means controlled by one of said switching means for increasing the gain of said amplifier.

'2. In a telephone system, a substation including a side tone reduction coil and a receiver circuit, an amplifier associated with said receiver circuit, and a shunt across the input path of said amplifier, said shunt including an element the resistance of which name to this specification this 15th day of v May 1919.

' JOHN F. TOOMEY.

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