Siemens AEI Auto Party Line Circuit by qfa20129

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									             SELECTION UNIT FOR AUTO PARTY LINE EQUIPMENT WITH
             SELECTIVE RINGING               AEI DRAWING NO XTW 80569

                                                                                                                                                           TO TELEPHONE
                                                                                                                                                           INSTRUMENT
                                             TB                                                                                                   TB
             B                      2             2A                                                                                         4A        4   red    B
TO LINE
             A                      1             1A                                                                                         3A        3   white A

             E                      8             8A
TO EARTH


                                                                   B                                    A
                                                             31                       40       1                              10




                                        15        25                   18       28                     NOTE 2

                                                                                17         27      12               14             13
                          b                              b
                                             5                              5
                    R1                             R2
                    47k                            47k
                      a        7                        a     7
                                                                                                                              Y2                  TB
                                                                                                                                             6A        6   green      R
                                                                                                                              21        22
                              V1                             V2                            b               e
                                                             Mullard                                                X
                              Mullard        2                              2         1500             8000
                              Z300T                          Z300T                                                  1
                                             b                              b              a               d
                                   MR1                            MR2
                                             a                              a
                                                                                                               23
                                                                                                   22                    24
                                        11         21                  16        26
                                                                                                                              Y1             5A
                                                                                                                                                  TB
                                                                                                                                                       5   blue
                                                                                      3
                                                                                                                                                                      H
                 NOTES                                                                X1           1                          1         2
                 1. THE BRACKETS SUPPORTING
                 THE COILS OF THE RELAYS TO                                                2
                 BE REMOVED BEFORE TESTING.
                                                                                           e
                 2. ALL UNDESIGNATED                                                                   Y
                 TERMINALS ARE ON BLOCK TA
                                                                                       6500            2
                                                                                           a




                                                  STRAPPING CHART NOTE 1
          STATION                                                                                                                                 PULSES
          CODE                          STRAP BLOCK TA AS SHOWN BELOW
          NUMBER                                                                                                                                  1ST      2ND

            1         5-15                        11-12                     16-17              22-23                      28-38                   +A       +B

            2         5-15                        12-13                     17-18              21-22                      26-36                   +A       -B

            3         1-11                        12-13                     16-17              24-25                      28-38                   -A       +B

            4         1-11                        14-15                     17-18              22-23                      26-36                   -A       -B

            5         8-18                        11-12                     16-17              22-23                      25-35                   +B       +A

            6         6-16                        12-13                     17-18              21-22                      25-35                   +B       -A

            7         8-18                        12-13                     16-17              21-31                      24-25                   -B       +A

            8         6-16                        14-15                     17-18              21-31                      22-23                   -B       -A

            9         12-13                       17-18                     21-22              25-35                      26-36                   +B       -B

            0         12-13                       16-17                     21-31              24-25                      28-38                   -B       +B

            11        5-15                        6-16                      18-17              21-22                      12-13                   +A       -A

            12        1-11                        25-24                     12-11              8-18                       16-17                   -A       +A
Circuit Description for Station strapped as No 6
The first pulse (+130V on the B leg) arrives via the strappings on the terminal block, 35-25, through V1
and MR1 and strap 21-22 to operate relay X over its d-e winding and strap 12-13 to earth. Contact X1
prepares the operate winding of relay Y.

The second pulse arrives immediately afterwards (-130V on the A leg) via strap 6-16 MR2 and V2,
strap 18-17, through relay X’s 1500 ohm winding and closed contact X1 to operate relay Y.

Relay X holds on its 1500 ohm winding and relay Y operates. After the second pulse a hold potential
of the same voltage as the second pulse (+130V) is applied to the A leg. Relay X releases first
because relay Y has a slugged coil making it slow to release.

Contact X1 now applies the Y relay coil via the Y1 contact and the telephone instrument A button to
the A leg. Relay Y thus holds to a 50V potential on the A leg. Contact Y2 applies earth behind the
telephone instrument ringer, which is connected to the B leg via the contacts of the telephone’s A
button. Ringing current is now sent out on the B leg and returns via earth.

When button A is pressed to answer, ringing ceases and relay Y releases, having been disconnected
by the A button.

Note: Tubes fitted are Mullard Z300T which will strike at 90V but not at 70V.

Additional notes from John Goldfinch

I have added codes 11 & 12, in purple, which may be valid strappings, comparing them with 9 & 0, but
not used because of the numbering system decided on for selection by use of a dial. Hence the extract
“By using a signalling earth return, coding each pulse either negative or positive and using each leg of
the line separately, a total of 10 independent selections could be made” is not strictly correct in logic
terms, but is correct for the system as devised.

And Mike Tyrrell adds:

John is correct in saying that the coding scheme would accept 12 codes because in the original
equipment, which was for a job in West Africa somewhere, it had lines of 12 phones.

When I specified for the permanent installations, we had a loan system to try of the African variety, I
wanted to use the standard Southern Region numbering scheme as this would readily transfer to ETD
(Extension Trunk Dialling) when the time came.

								
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