Jan. 19, 1943.
`
`L.
`vi, PRINCE, JR
`AUTOMATIC TELEPHONE SYSTEM
`Filed Sept. 11, 1939
`
`2,308,778
`
`3. Sheets-Sheet, l.
`
`(?)
`
`
`
`NVENTOR
`
`Ex. 1017
`CISCO SYSTEMS, INC. / Page 1 of 11
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`

`

`Jan. 19, 1943.
`
`L. M. PRINCE, JR
`AUTOMATIC TELEPHONE SYSTEM
`
`2,308,778
`
`Filed Sept. ll, 1939
`
`3. Sheets-Sheet 2
`
`
`
`lite
`
`N N
`
`"INVENTOR
`ita\ 3...ey
`
`Ex. 1017
`CISCO SYSTEMS, INC. / Page 2 of 11
`
`

`

`Jan. 19, 1943.
`
`L. M. PRINCE, JR
`AUTOMATIC TELEPHONE SYSTEM
`Filed Sept. ll., 1939
`
`2,308,778
`
`3 Sheets-Sheet 3
`
`2OW
`
`22
`
`
`
`too ov
`36
`
`t
`
`FIG.
`
`9.
`
`4.
`
`5
`
`().
`
`
`
`
`
`
`
`
`
`i.
`
`3 as
`
`93
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`
`
`IPISIS
`(lit.
`few Guich
`
`Ex. 1017
`CISCO SYSTEMS, INC. / Page 3 of 11
`
`

`

`Patented Jan. 19, 1943
`
`2,308,778
`
`UNITED STATES PATENT OFFICE
`
`2,308,778
`AUTOMATIC TELEPHONE SYSTEM
`Leon M. Prince, Jr., New York, N. Y.
`Application September 11, 1939, Serial No. 294,230
`(CI, 179-8)
`14 Claims.
`aS is Well known in the automatic telephone art,
`This invention relates to electronic control cir
`is Suitably operated to connect the proper sub
`cuitS and more Specifically to application of such
`Scriber circuit to the trunk line.
`circuits to automatic telephone systems.
`In order to save duplication of equipment in
`The accompanying Figures 1, 2 and 3 repre
`the register circuit, Fig. 3, the telephone com
`sent an all-electronic register circuit for a panel
`pany uses only a few of the numbers from 1 to 0.
`Sender of a dial telephone system. It is designed
`Just five units are used in this code but these five
`for use With telephore numbers comprised of
`units are made to do the Work of ten. These
`Seven units, e. g., tile numbers used in New York
`unitS are 1, 2, 4, 5, and 2, the latter representing
`city. The circuit is subdivided into three main
`the character 0. The dialing of the number 1 or
`circuits and two auxiliary control circuits. The
`a letter corresponding to it is represented by 1;
`first main circuit, Figure 1, is called the “count
`the dialing of the number 2 or a letter corre
`ing circuit' and is comprised of tubes A- to
`Sponding to it is represented by 2; the dialing
`A-3. The second main circuit, Figure 2, is
`of the number 3 is represented by 2 and 1 in com
`called the “differentiating circuit' and consists
`bination; the dialing of 4, by 4; the dialing of
`of tubes B- to B-13. The third main circuit,
`5, by 5; the dialing of 6, by 5 and 1; the dialing
`Figure 3, is called the “register circuit' and is
`of 7, by 5 and 2; the dialing of 8, by 5, 2 and i,
`comprised of tubes C-5, C-7, C-, C-2, C-4,
`the dialing of 9, by 5 and 4; and finally the dial
`C-5, and C-Z. . . . . . . . . J-6, J-7, J-?,
`iing of 0, by 2 alone.
`J-2, J-4, J-5, and J-Z. Auxiliary reset cir
`The counting circuit, Fig. 1, counts out the
`20
`cuits are comprised of apparatus K-1, K-2, and
`total number of impulses in each series of clicks
`I-, shown in Fig. 2.
`as the dial sends them out. The function of the
`For the purpose of illustrating the cooperation
`differentiating circuit, Fig. 2, however, is to take
`of the three circuits a brief description of a typi
`these dialed impulses and codify them so that
`cal automatic telephone dialing system is includ
`the output circuit of the differentiating ap
`ed. When a telephone subscriber wishes to dial
`paratus actuates the proper lines of the five lines
`a number, e. g. Endicott 2-7769, he places his
`corresponding to the numbers 1, 2, 4, 5, and g of
`finger in the opening of the dial showing the
`the code. These lines in turn will supply operat
`letter E and pulls the dial around to the stop
`ing potential for the grids of each set of tubes in
`When the dial is released the dial clicks. 30
`bracket.
`the register groups, Fig. 3. For example, on the
`off three signals. Next, he places his finger in the
`Second dialing operation corresponding to the
`opening showing N and again pulls the dial
`letter N, six impulses will be received by the
`around to the stop bracket. Upon releasing it,
`counting circuit shown in Fig. 1. This will op
`the dial clicks off six Siginals. Then he dials the
`erate Six odd-numbered tubes in the counting
`number 2 and the dial clicks off two signals.
`( 35
`circuit which in turn will operate corresponding
`This is repeated for the numbers 7, 7, 6, and 9 in
`tubes in the differentiating circuit shown in Fig.
`order, and each time the dial clickS off signals
`2 SC as to put operating potential on lines 5 and 1
`corresponding to the number dialed.
`of its output circuit.
`Each of these clicks is transformed into an
`AS a result, tubes D and D5 in the second
`electrical impulse and it is the purpose of my
`group of tubes in the register circuit shown in
`40
`counting circuit, Fig. i., to count each one of
`Fig. 3, will be operative, indicating that the
`these impulses. Thus, on the first series of in
`Second unit of the telephone number dialed is N
`pulses corresponding to the letter E, the count
`(or 6). In the Sane Way, the operation of tubes
`ing circuit will record 3. It is there reset, as it
`C and C2 in the first register group indicates
`Upon
`is after each Successive series of impulses.
`:43
`that the letter E (or 3) is the first letter of the
`th2 second series of impulses corresponding to
`number dialed. The operation of tube E2 in the
`the letter N it will record 6. Upon the third
`third register group indicates that the number 2
`Series of impulses, corresponding to 2, it Will
`is the third inlinber dialed. This continues down
`record 2. This Will be continued until all the
`the line until tubes is and 4 in the bottom group
`ninnbers are counted. After counting each Series
`50
`of tubes operate to indicate that 9 was the final
`of impulses, the counting circuit sends its count
`number dialed. How these results are accom
`to the differentiating circuit, Fig. 2, which actu
`plished by ny circuit is described in greater detail
`ates circuits corresponding to the count which in
`hereafter.
`turn actuate the register circuit, Fig. 3, to record
`D. C. potential is Suplied to the plates of all
`the result and cause the number to be connected.
`tubes. In the present arrangement gas-filled
`The counting circuit and the differentiating cir
`tubes are used having operating characteristics
`cuits are then claared and are ready to receive
`Such that a plus bias of 20 volts on the grids is
`the next series of impulses. The register circuit
`required to render them operative. Any tubes
`is not reset until the whole series of numbers
`With Similarly suitable characteristics may, of
`have been recorded and retransmitted to an auto
`course, be Substituted.
`matic switching apparatus (not shown) which,
`
`5
`
`O
`
`25
`
`55
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`60
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`
`Ex. 1017
`CISCO SYSTEMS, INC. / Page 4 of 11
`
`

`

`10
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`25
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`2
`2,308,778
`Referring to Figure 1, it is the purpose of the
`on the second impulse but is ready to respond to
`counting circuit to count the impulses of the dial
`a third impulse.
`and to transmit the results of this counting to
`in this fashion each successive pair of tubes
`the differentiating circuit. This circuit is con
`will operate as long as the dial sends out impulses.
`posed of a Series of pairs of tubes A- and A-2,
`The value of l'esistor 5 in the plate circuit of
`A-3 and A-4, through A-7 and A-18, and
`tube A- Controls the current in resistor 4f So
`the single tube A-9. Each pair is comprised of
`that the IR drop is 20 volts, or more. Resistor 52
`a primary and secondary tube, the secondary
`in the plate circuit of tube A-3 performs the
`tube in each instance acting to prepare the foll
`Sane function for l'esistor 43, as do all the other
`lowing primary tube for operation. The single
`resistors in the plate circuits for the resistors in
`tube A-9 does not require a secondary tube
`the cathode circuits of the primary tubes. The
`because it is the last tube in the line and there
`value of resistor 3 in the plate circuit of tube
`fore has no corresponding Secondary tube to pre
`A-2 controls the current in cathode potentiom
`pare for operation. All the odd numbered tubes
`eter 42 so that the IR drop equals approximately
`in group A are primary tubes and the even num
`129 volts. Similarly, resistor 55) in the plate cir
`bered are Secondary tubes. The grids of all the
`cuit of tube A-4 performs the same function for
`primary tubes are in parallel and connected with
`cathode potentiometer 44 as do all the resistors
`input line 2 , 9. This input line 3, 2 is ar
`in the plate circuits for the cathode potentiom
`ranged to respond to the dialed number by
`eters of the secondary tubes.
`temporarily raising the potential of the com
`After each series of impulses corresponding to
`20
`mon primary grid line 25 from ground potential
`a. Single number of the telephone number to be
`to Some higher value, i. e., 20 volts, for each
`dialed, the currents in the plate circuits of the A
`dial click received over line 9, 2 . This grid
`tubes are tenporarily interrupted by means of
`potential impulse is timed by a suitable time con
`relay contacts 22 and 24 in Figure 2, and they are
`stant circuit to die out in a predetermined time
`all reset and immediately ready to operate again.
`interval before the next dial click is received.
`The sequence of events resulting is this opera
`Thus the grid line 25 will receive a series of sharp
`tion Will be hereinafter described in connection
`transient impulses, i.e., a series of 20-volt pulses,
`With the circuit.S Shown in Figure 3. In addition
`spaced in a predetermined manner, the number
`to Supplying grid control potential for their
`of which impulses will correspond to the number
`corresponding Secondary tubes, these potentiom
`30
`of dial clicks received, i. e., to the digit dialed.
`eters, i. e., the resistors in the cathode circuit
`Thus, upon the first impulse of a given series
`of the primary tubes, also control the grid cir
`corresponding to a given number from 1 to 0
`cuits of tubes B- through B-13, shown in Fig
`Which is dialed, the grid of tube A- Will lose
`ure 2, to which they are connected by lines 3
`control. Current Will then fiOW fron Source of
`through 43.
`potential of 120 volts at power supply K-2 of
`As an eXangle of the actual cperations of the
`Figure 2 through line 53, through current limit
`circuits just described in connection with Fig
`ing resistor 5, tube A-, and cathode resistor
`ure 1 let us dial the telephone number Endicott
`4 to ground. As a result line 3 Will assume a
`2-7769. Translating this telephone number into
`potential of 20 volts instead of its original po
`40
`figures it becomes 3-6-2-7769. In accordance
`tential of Zero. One of the results of this change
`with this sequence of numbers, the counting cir
`in potential is to charge the condenser 46 through
`cuit Will first operate so that a potential of 20
`resistor 45 which, after a time delay com
`volts will be on lines 3, 32, and 33. After the
`mensurate With values of said condenser and re
`dial returns to rest, relay contacts 23 and 24 Will
`sistor, will cause the grid of tube A-2 to lose
`45
`Operate interrupting the plate circuits and reset
`control. Operation of tube A-2 permits current
`ting all tubes in the counting circuit (and in the
`from source of potential of 1000 volts at power
`differentiating circuit, Fig. 2, as Will hereinafter
`supply K-2 in Figure 2 to flow through line 54,
`be explained). The next series of impulses is 6,
`current limiting resistor 49, tube A-2, and
`So lines 3 f to 33, inclusive, will have operating po
`cathode potentiometer 42 to ground. The IR
`50
`tential On them. After the next interruption,
`drop across potentiometer 42 raises the Cathode
`lines 3 and 32 will possess operating potential.
`anode potential of tube A-3 from zero to ap
`After the next two interruptions lines 3 to 37, in
`proximately 120 volts. But by this time the first
`clusive, Will possess operating potential. After
`impulse on line 25 has died Out Since the time
`the next interruption, lines Sf to 36, inclusive,
`delay in condenser AS and resistor 45 is so ad
`will possess operating potential. Finally, after
`55
`justed that tube A-2 will operate some time
`the next interruption, lines 3 to 39, inclusive,
`after the first impulse occurs but before the
`Will possess operating potential. Upon the dial's
`Second one. Therefore, A-3 cannot operate on
`return to rest after this final signal, the plate
`the first impulse. Bafore the second in pulse oc
`circuits will be interrupted once more, clearing
`curs, howevers, the IR drop across resistor 42 is
`the group A tubes for a new incoming call.
`60
`Sufficient to supply A-3 with a plate potential of
`The function of the differentiating circuit
`120 volts and therefore A-3 is ready to operate
`ShOWn in Figure 2 is to record the results of the
`if and when the second impulse occurs. When
`counting circuit shown in IFig. 1 in such a way
`the grid of tube A-3 loses control as a result
`as to make these signals available for use in the
`of a second impulse on line 25, current flows from
`register circuit lines , 2, 4, 5, and a connecting
`the 120 volt source of potential across the
`the differentiating circuit of Figure 2 with the
`cathode potention eter 4 of tube A-2 through
`register circuit of Figure 3. The tubes in this dif
`a, current limiting resistor 52, tube A-3, and
`ferentiating circuit are, in a sense, arranged into
`Cathode resistor 33 to ground. As before, tube
`Six groups. They are (1) tubes B-, E-2, and
`A-A does not operate luntil after the Second
`B-4, whose plates are connected together to a
`impulse has subsided and before the third one
`Single series resistor 55 and thence to a 120 volt
`begins. Thus, the potentiometer 4 in the
`SCurce of potential; (2) tube B-3, the cathode
`cathode circuit of tube A-4 does not Supply tube
`of Which is connected to the cathode of tube B
`A-5 with plate voltage until just after the Second
`but through its own plate resistor f4 to approxi
`impulse dies out. Thus tube A-5 cannot Operate
`mately 160 volts at source K-2; (3) tubes B-5.
`
`35
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`65
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`70
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`75
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`Ex. 1017
`CISCO SYSTEMS, INC. / Page 5 of 11
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`

`

`O
`
`20
`
`3
`2,308,778
`condition to render operative the register tubes
`B-6, and B-7, whose plates are all connected to
`(Fig. 3) connected to them, both C- and C-2.
`Series resistor 3 thence to 120 volts at Source
`When line 34 receives potential due to a fourth
`K-2; (4) tubes B-8, B-9, and B-, whose
`impulse, tubes B-6 and B-5 operate. The Op
`plates are connected together and receive plate
`potential through series resistor 58 and line 6
`eration of tube S- dra WS So nuch current
`through resistor SS as to greatly increase the
`from a plus 1000 volt source at K-2; (5) tube
`IR drop across it. This affects the drop acroSS
`B-O the plate of which is connected through re
`resistOS 52 and 3 Which in turn reduces the
`sistor 57 to a plus 160 volt source of potential at
`potential of points g- and p-3 and so of lines
`K-2 and the cathode of Which is connected to
`and 2 to below 20 volts, at which value they
`the cathode of tube B-3 through resistor 6; and
`are incapable of rendering operative the register
`(6) tubes B-2 and B-3 Whose plates are coin
`tubes shown in Fig. 3 connected to thern. Upon
`nected together and obtain piate potential Of 120
`the simultaneous operation of tube B-5 current
`volts through series resistor 58. Within each
`foWS in resistor i? and the IR, drop across it
`group, as each Successive tube operates, the IR
`raises the potential of point p-s, across the po
`drop across the series resistor reduces the p
`5
`tentionetter formed by resistors Gil, 2, 73 and 74
`tential at the cathode by an equal amount. In
`to 20 volts. Line 4 thus acquires a potential of
`any group therefore, an operating potential on
`20 volts and is capable of rendering operative the
`line , for example, is reduced to a non-Op.8ating
`register tubes connected to it.
`potential through the decrease in current flowing
`Upon the operation of tube B-6 as a result
`through resistor 62 of tube 3- when tube B-2
`of Operating potential On line 35 due to a fifth
`or B-4 operates. The same principle applies
`impulse, the potential of point p-5 and so of
`throughout the six groups. When it, is desired to
`line 5 is raised to 20 volts, rendering it capable
`lower the operating potential on all the cathodes
`of operating tubes connected to it. The Value
`of any one group, a tube, Such as 3-i, is shorted
`of resistor 65 is greater than that of 64 so that
`through the Series resistor to ground. This in
`When tube E-6 operates the IR drop acroSS re
`creases the IR drop thirough the Series resistO to
`sistor 65 is sufficient to give point p-5 a poten
`a value far below that required by the Various
`tial of 20 volts, but the drop across resistor f3
`cathodes to Supply Operating potential to the cut
`is now so large that the potential of point p-4
`put lines of the circuit. The operation of the dif
`drops below 20 volts, rendering line 4 incapable
`ferentiating circuit, Will now be traced. When the
`of operating tubes connected to it.
`grid of tube B- loses control as a result of po
`The potential of p-5 remains 20 volts during
`tential on line 3 die to a first inpulse of any
`the next four signals from the counting circuit.
`number of a dia.ied telephone number, current
`Upon a signal from line 4, however, the opera
`flows from the plus 120 volt Source of potential at
`power supply K-2 through Series resistor 55,
`tion of tube B-. So increases the IR drop acroSS
`tube B-, and through cathode potentiometer 82
`series resistor 3 as to greatly reduce the IR
`drop across resistor 65. As a consequence the
`to ground, and also through resistors 6, 6 and
`68 to ground, but not through line , the grids of
`potential of p-5 and line 5 is reduced to a value
`less than 20 volts, rendering it incapable of op
`- tubes in Figure 3 to ground, as none of these
`grid to cathode paths are yet open. The result is
`erating tubes connected to it.
`Upon the operation of tube B-8 as a result
`to raise the potential of point p- fron Zero to 20
`of potential on line 36 due to a sixth impulse,
`volts, placing 20 volts on line . If no further in
`pulses are received this grid potential Will be
`current flows in resistor 68. The TR, drop across
`this is 100 volts (the potential on line 76 is 1000
`sufficient to operate tube C- in the first group
`volts) with the result that the potential of p
`of the register circuit (Fig. 3). Upon the opera
`and line
`on the potention eter is raised to 20
`tion of tube B-3 as a, result of potential or
`volts again. The value of the current through
`line 32 due to a second implse of any nusabar
`resistors
`and S8 should be ten times that
`of a dialed number, current fioWs in resistor
`,
`through 6 and 66; the value of resistor 6
`the value of which is greater than resistor 2
`through a path parallel to the path of current
`should be fol: times that of SS. Thus, With
`potential on line 3S indicating the reception of
`through tube E-. As a result, point 2-2 as
`sumes a potential of plus 20 volts through resistor
`the sixth impulse from the dial, the differenti
`atting circuit has placed an operating potential
`S9, as does also line 2. This potential Will on
`erate tube C-2 in the register group (Fig. 3),
`Of 20 volts on lines 5 and .
`Upon the operation of tube B-3 as a result,
`providing no further impulses are received. The
`of potentials on line 37 due to a seventh in
`current through resistors 62 and 63, however, also
`pulse, current flows in resistor i, the value of
`goes through the series resistor 55 with the re
`sult that, upon the operation of B-2, the
`which is greater than 63. The result is to raise
`the potential of p-2 and line 2 to 20 volts
`current through 62 is reduced and thus the
`voltage of point p- and so of line
`drops
`again, and, because the drop across resistor 58
`is increased by the operation of E-9, the drop
`to a value less than 20 volts, rendering this
`line incapable of operating tuhe C-. I a
`across 68 is decreased and so the potential of
`this way the counting and differentiating cir
`point p- and line is reduced to below 2 volts,
`rendering it, incapable of operating its register
`cuits Will function. So as to Only render op
`tubes (Fig. 3). As before, the values of resistors
`erative tube C-2 of the first register group as a
`G3, 63, T2, and
`are proportional to 62, 66, 67,
`result of the Second dialed inpse. Upon th;
`and 68, respectively.
`operation of tube R-3 as a result of potential
`Upon the operation of tube B- as a result
`on line S3 caused by a third impulse, current flows
`of potential on line 38 due to an eighth in
`in resistor A. from a Source of 160 WotSpotentia.
`pulse, the potential of p- and line
`is again
`at K-2, through tubes B-3, and through re
`raised to 20 volts, due to the increase of the
`sistors 62 and 66, 7 and 8 to ground. The result,
`current flow through 6 and 8 and 66 and 62
`is to raise the potential of p-i and line 1 to 2
`due to the opening up of another electrical
`volts again. Thus, when three impulses have
`channel through tube B-0 and resistor 5, to
`been recorded by the counting circuit, lines
`a source of potential of 160 volts in the power
`and 2 out of the differentiating circuit are in a
`
`35
`
`40
`
`5 5
`
`60
`
`Ex. 1017
`CISCO SYSTEMS, INC. / Page 6 of 11
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`

`

`O
`
`0
`
`i)ial impulse No.
`
`Potential on differentiator output lines
`
`Line 1 Line 2 Line 4 Line 5 Line Z,
`
`3 5
`
`4.
`2,308,778
`supply X-2. Thus, register tubes connected to
`This potential change will induce a transient
`lines 5, 2, and f can operate. When B- op
`through transformer 28 onto the grid circuit of
`erates as a result of potential on line 39 due
`Vacuum tube K- Figure 2. This temporary
`to a ninth impulse, the drop across resistor 58
`change in grid bias of tube EX-1 will cause the
`is increased so that the potential of points p
`fast electromagnet relay 20 in its plate circuit
`5
`and p-2, and, cf course, lines
`and 2, drops
`to be monentarily energized, drawing current
`to below 20 volts again. The sinnultaneous Op
`from plus 120 volts at power supply L- through
`eration of B-2 causes current to flow through
`line 88, relay 20, tube K- and thence to ground.
`resistor 74 and, in the same Way as before, the
`As the relay becomes energized, its contacts 23
`potential of p- and line 4 is raised to 20 volts
`and 24, moimentarily open, interrupting the
`again, making it possible fol' register tubes con
`Source of potential to power Supply K-2 from
`nected to lines 5 and 4 to Operate.
`supply lines 43 and 44. This will momentarily
`Finally, upon the operation of tube B-3 as
`reduce the plate Voltage of all the gaseous-dis
`a result of potential on line 40 due to a tenth
`charge tubes in Figures 1 and 2 to zero. As a
`(or Zero) impulse, current flows through re
`Consequence all the grids Will regain control and
`sistor T5 which is greater than 73 raising the
`the counting and differentiating circuits will be
`potential of p-2 and line 2 to 20 volts. The
`immediately ready for another series of incom
`increased IR drop across resistor 56 reduces the
`ing signals from the dial input line, 2, 9. This
`current through 74 and thus the potential on
`cycle of cperations Will be repeated each time
`p-4 and line 4 to below 20 volts. Simultane
`the dial cones to rest against the bracket after
`ously, as previously described, the Operation of
`a given number is dialed.
`B-T has reduced the potential of p-5 and line
`Upon the next set of impulses from the dial
`5 to below 20 volts. Thus, as a result of poten
`the counting circuit will put potential on lines
`tial on line 4) only line a remains With 20 VoltS
`3, 32, 33, 34, 35, and 36, and the differentiating
`on it and only tubes connected to line 2 can op
`circuit Will operate to put 20 volts on lines 5
`erate.
`and . Dialing 2 will Will put 20 volts on line
`A capitulation of the results attained by the
`2: dialing 7 twice will put 20 volts on lines 5
`differentiating circuit is contained in the follow
`and 2 tWice in Succession; dialing 6 will put 20
`ing table:
`Wolts. On lines 5 and ; and dialing 9 will put 20
`B means tube is operative
`volts on ines 5 and 4. Upon the final return
`X means tube is not operative
`of the dial to rest the operation of tube K-f
`Will reset the differentiating circuit and it will
`then be ready for a new set of signals.
`The function of the register circuit, Figure 3,
`is to receive the results of the counting and
`codification of the dialed impulses and to ac
`tuate apparatus in the unit following the panel
`Sender corresponding to the numbers dialed,
`This apparatus is represented by circles in the
`plate circuits of the tubes of the register groups.
`The resistor circuit is divided into seven groups
`of tubes, C-tubes, D-tubes, E-tubes, F-tubes,
`G-tubes, H-tubes, alld J-tubes, each group
`of which registers in the code the impulses of
`a single nuinber dialed. Each group is subdi
`vided into two sets of tubes. Tubes numbered
`-, -2, -4, -5, and -2, called the main
`register circuit tubes, record the signals on the
`output lines of the differentiating circuit, tubes
`numbered -3 and -7 count the dial stop sig
`nals at the end of each dialing cperation and
`function to transfer the output signals of the
`differentiating circuit to successive groups of -
`to -2 tubes. Thus, the first dial stop signal
`from lines 22, 8 serves to put group C in action,
`the Second dial stop signal puts group D in ac
`tion, and So forth to the Seventh and last dial
`Stop signal Which puts group J in action. When
`the Subscribe noves the dial away from the
`rest position as he begins to dial the desired
`number, nothing happens in the register circuit
`Figure 3. Nothing happens in the circuit as he
`winds the dial to the desired digit or letter of
`the number and nothing happens in the register
`circuit as the dial is released and clicks out its
`signals. But when the dial returns to rest after
`this operation, the dial stop signal sends its
`impulse through input lines 22, 3 to the grids
`of all -T tubes in Figure 3, temporarily rais
`ing their potential to 20 volts or more. In the
`meanWhile the Counting and differentiating cir
`cuits have picked up the signals of the dial in
`put line 2, 9 and have placed operating po
`tentials Oil lines , 2, 4, 5, and 2 in accordance
`With the number dialed and the code it repre
`
`Dialing 3-6-2-7769 will produce potentials
`on the following output lines of the differenti
`atting circuit:
`Dialing “3' will place operating potentials On
`output lines 3 S, 32, and 33 of the counting Cir
`cuit (Fig. 1) and will put operating potentials of
`plus 20 volts on lines and 2 shown in Fig. 2.
`Upon the return of the dial to rest, the dial
`stop signal will operate. This dial stop signal
`like the regular dial signal is a transient in
`pulse of 20 volts or more and is represented in
`5 5
`Figure 3 as input line 22, 3. This dial Stop
`signal controls the grids of tubes C-6 and C-7,
`D-6 and D-T . . . J-S and J-7 a Series of
`seven pairs of tubes, primary and Secondary,
`exactly equivalent to the pairs of tubes in the
`counting circuit of Figure 1. The function of
`these latter tubes, however, is not Only to count
`the impulses sent cut by the dial stop signal
`but by their operation to place suitable plate
`potential at the proper instant upon register
`tubes C-1, C-2, C-S, C-4, and C-5; D-,
`D-2, D-3, D-5, and D-5; . . . J-, J-2,
`J-3, J-3, and J-5 after receipt of each Suc
`cessive dial stop signal. The drawing of Cur
`rent by any of the C-6, D-fi . . . J-6 tubes
`from source of supply L-f Figure 2, through
`resistor 35, line 2S, the current regulating re
`sistor in each plate circuit, a -6 tube and thence
`through its cathode potentiometer to ground, Will
`create a small IR drop across the resistor 80.
`
`
`
`() X {
`S
`i------------------------- B 20 X () N 0
`0
`3,
`25, X ON ON 0
`20 B 29 N () X () X ()
`6 X 0 B 20 X 0 X 0
`G Y 10
`X 0 B 20 X 0
`20 N. 10 X 10 B 20 X 0
`() B 20 X 10 B 20 N ()
`29
`2: X 10
`B 20 N
`()
`6 X 10 B 20 | B 20 X 0
`6 : X
`S ON 10 B 20
`10
`
`45
`
`60
`
`w 3)
`
`Ex. 1017
`CISCO SYSTEMS, INC. / Page 7 of 11
`
`

`

`5
`
`10
`
`20
`
`5
`2,308,778
`through the tubes in parallel thence via resistor
`sents. But even the operation of a - tube in
`9 to ground. The drop across series resistor 9
`Figure 3 does not permit -f, -2, -4, -5,
`Will raise the bias on the grids of the remain
`Or -2 tubes in the main register circuit to op
`ing non-Operative tubes in this C-group to a
`erate, even though operating potential is avail
`point Where they can no longer lose control until
`able on their grids. These main register circuit
`a plate circuit interruption reduces the bias
`tubes must Wait until after the dial stop signal
`through resistor 9.
`has died out before a -6 tube, which is con
`Because of the time delay in the operation of
`trolled by time delay circuit in its grid, exactly
`tube C-6 after the dial stop signal to the grid
`as in the counting circuit of Figure 1, puts cur
`of tube C-7, tube D-7 has been prevented from
`rent through the potentiometer in its cathode.
`Operating On the first dial stop impulse. As a
`These -6 tubes receive plus 1000 volts plate
`consequence potentiometer 82 in the cathode of
`potential from source I-, Figure 2, through
`tube -6 cannot Supply plate Voltage to the
`resistor 80, line 26, an individual current limit
`D group Cf register tubes. Thus, these do not
`ing resistor in each of their plate circuits, thence
`respond to the operating potentials on input
`through the tubes and the potentiometer in each
`lines to 2 corresponding to the first set of im
`Cathode to ground. The potential across the
`pulses sent cut by the dial. Similarly groups E,
`potentiometer is 120 volts and the current
`it, G, H, and J do not respond.
`through it should be at least ten times the maxi
`The operation of tube C-6 also causes cur
`mum load (three operative tubes) that the main
`rent to flow through resistor 80 which in turn
`register circuit tubes -, -2, -4, -5, -8 Will
`transmits an impulse to the transformer in the
`draw. The -i tubes in Figure 3 operate as
`grid of vacuum tube K-l. This responds to
`follows: Tube C-1, in a similar Way to tube
`the impulse in Such a way as stated before as
`A- of Figure 1, is connected from a 120 Volt
`to actuate relay 29 just long enough to mo
`source of supply at I-? in Figure 2 through line
`mentarily open contacts 23 and 24. This clears
`27 and, current limiting resistor 45, to a grid
`the counting circuit and differentiating circuits
`bias resistor 46, which controls tube C-6, and
`for the next set of impulses from the dial but
`thence to ground. The remaining - tubes are
`not before the old Set has been recorded by the
`connected in the Sarine manner except that they
`first register group of tubes. Upon each suc
`obtain their plate voltage supply from across the
`cessive signal from the dial stop line 22, 8 and
`potentiometer in the grid of the preceding -6
`the subsequent operation of a -6 tube, resistance
`tube, for example, tube D-7 obtains its plate
`8. Will receive an additional increment of cur
`supply from potentiometer 8 in the cathode of
`rent through it. Each increment serves to ac
`tube C-6.
`tuate E- and relay contacts 22 and 24 and
`How the register circuit of Figure 3 functions
`so to reset the counting and differentiating cir
`as an entity will now be described in some de
`3 5
`cuit. The value of 80 must be large enough to
`tail. Upon the first dial stop signal or input
`create the desired effect in the vacuum tube but
`lines 8, 22, C-7 operates (since it is connected
`must not be so large as to materially effect the
`directly to a plus 120 volt line), and through a
`potential on the plates of the -6 tubes with
`time delay circuit exactly as in the counting
`Which it is in series. In addition, upon each Suc
`circuit shown in Figure 1, Tube C-6 operates.
`40
`cessive signal from the dial stop line 22, 8 and
`Current then flows in resistor 8 across which
`the subsequent operation of a -6 tube, Succes
`are connected in parallel tube D-7 including its
`sive register groups will receive plate potential
`cathode resistor 49 and plate resistor 4 and
`from the potentiometers 82, 83 . . . 87 in the
`tubes C- through C-2 inclusive with their
`Cathodes of these -6 tubes in such sequence
`associated common cathode series resistor 9.
`The grids of these tubes C-1 through C-2 Will
`that groups D, E, F, G, H, and J will be rendered
`then respond to whatever signals have been Set
`operative in that order.
`As each Set of impulses from the dial is trans
`up in lines
`to 2. If more than one line has
`an operating p