Patent GB-191107852-A (GB)
Title: Improvements in Automatic or Semi-automatic Telephone Exchange Circuits.
IPC: H04Q1/32
Filed: 1911-03-29
Granted: 1911-11-02
Abstract: 7852. Siemens Bros. & Co., [Siemens & Halske Akt.- Ges.]. March 29. Semi-automatic exchange systems. - Impulse - transmitting sets are organized so that no time is wasted between the sets of impulses representing different digits. Special side switches are provided for this purpose. The figure represents a threedigit impulse set for use by a central-station operator in extending connexions from a calling to a called subscriber by means of automatic instruments. A set of keys is provided for each digit of the subscribers' numbers, and illuminated indicators are controlled from these keys (in a manner not described) so that a mistake in setting is made evident and can be rectified. The selective instruments may be operated by interruptions in the a line while the b line is earthed, as described in Specification 9634/10. The operations when subscriber No. 838 is to be called are as follows. The operator depresses the eighth, third, and eighth keys H<8>, Z<3>, E<8> of the hundreds, tens, and units series and operates a switch K to connect the leads a, b to the leads az, bz of a first selector. Self - locking relays h<8>, z<3>, e<8>, associated with the keys H<8>, Z<3>, E<8> are energized and ground the eighth, third, and eighth contacts of rotary switches k, belonging to the hundreds, tens, and units transmitters JH, JZ, JE. The magnet S of a side switch is momentarily energized by a rotary interrupter U and battery B owing to the closing of contacts 7, 9, and the side switch arms S<1>, S<2>, S<3> move on to the contacts 1, grounding the selector leads a, b over the arm S'. The magnet S is now again energized over the lead 12 and moves the arms S<1>, S<2>, S<3> on to the contacts 2, so that impulses are supplied from the interrupter U over the lead 15 to the rotary magnet Dh of the "thousands" switch k and back through the arm S<3> and the battery B. At each impulse the magnet Dh opens the a line at the contact ih and so sends a vertical impulse to the first selector. When the arm k reaches the grounded eighth contact, current is supplied to the winding 1 of a relay Tr, which locks up over a second winding 2, opens the circuit of the rotary magnet Dh at 14, and closes at 18 the circuit of the interrupter U and side-switch magnet S. The side-switch arms are thus moved on to the contacts 3, and then again, owing to impulses received over the lead 12, on to the contacts 4, 5. The arm S<1> in passing over the contact 3 opencircuits both leads a, b so that a rotary impulse is sent to the first selector. By the time the sideswitch arms have reached the contacts 5 a sufficient interval has elapsed to prepare for the "tens" impulses, which are then dispatched by the " tens " transmitter JZ. Similarly, when the side-switch arms reach the contacts 8, the " units " transmitter JE sends the " units " impulses. Finally a release magnet M is energized by the interrupter U over the contact 20 of the relay Tr and the corresponding contacts in the transmitters JZ and JE, but means are provided for delaying the action of this magnet until the necessary testing and other operations have been completed. The magnet M by opening the contact 2 releases the cut-off relays Tr and key relays h<8> &c. and the rotary magnets Dh &c. are intermittently energized by the interrupter U over the contacts d, 14 until the contacts dare opened by the arms k returning to normal position. The magnet M also releases the side switch and closes at 22 the circuit of a supervisory relay UR, which locks up over the contact 23. A supervisory lamp UL notifies the operator that the switching processes have been completed,