Patent GB-328340-A (GB)
Title: Improvements in or relating to timing apparatus, particularly for use in connection with telephone systems
IPC: H04M3/12
Filed: 1929-02-01
Abstract: 328,340. Automatic Telephone Manufacturing Co., Ltd., and Ostline, J. E. Feb. 1, 1929. Automatic exchange systems.-Timing apparatus for making observation of a number of intervals from a starting point comprises a pair of rotary switches, one of which is stepped at regular intervals to mark successive contacts in the banks of the second switch which chases the first. An indicating disc is provided on the shaft of the second switch which may be stopped by an operator to take a reading, and when re-started, quickly catches up to the first switch. The second switch may indicate seconds and drive a third switch on every tenth step so that if 50-point switches are used, intervals extending over 499 seconds may be timed. The apparatus is particularly applicable for use at an observation post in automatic telephone systems. Connection of observation equipment to line. The tapping of a line to be observed may be effected as described in Specification 305,158 except that in the present case connection is made directly to subscribers' line and not to the trunks outgoing from the line switches. The observation equipment is connected up for outgoing calls only, and for this purpose subscriber's line relay is shunted by a winding of a relay which, on initiation of a call, pulls up before the line relay energizes to ground the private conductor, locks over a second winding, removes the shunt on the line relay, switches through to the observation equipment, and disconnects a further relay from the private conductor. For incoming calls, the grounding of the private conductor energizes said further relay which cuts out the switching relay. When the plug P is inserted by the observing operator in one of the two jacks shown in Fig. 1, ground from 61 is connected over RK, MD, 16 to engage a high resistance relay (not shown), relay MD remaining inert. The high resistance relay connects ground to 4, and assuming that the armature of CX was left in the opposite position to that shown, CX(iv), XA and XB energizein turn, a holding circuit for CX(iv) being completed over resistance 31. When a calling line is connected to the observation equipment, conductors 2, 3 are looped and 1 is grounded so that a relay (not shown) connected to 88 switches in an amplifier of which 89, 90 and 91, 92 are the input and output terminals respectively. Relay TK operates over 21, TA, 1 and energizes G which locks up over RK and lights up lamp GL, the circuit of lamp PL being completed by TK so that this lamp glows so long as the line is looped. Relay TA does not energize at this time. Timing apparatus, Fig. 2. Relay S is energized' by relay TK and connects pulse conductor 20 to two-step relay Q which connects the pulse conductor to back-stroke magnet DM1 of switch CS. driving at one step per second. The switch CS. and also the tens and units switches TS, US, are 25-point rotary switches with two sets of wipers at 180‹, equivalent to 50-point switches. Relay S also completed a circuit over wipers 1 of US and OS for relay W which opened a point in the circuit of magnet DM2 of US. When switch CS has taken one step, W falls back, and T pulls up over wiper 3 and locks to complete the circuit of back-stroke magnet DM2 which removes the short-circuit around R so that the magnet restores and drives US one step, and relav W again energizes over wipers 1 of US, CS. The operator may, by pressing key SK, stop the switch US to take a reading from the disc on its shaft, and on release of SK, the switch will, under the control of R, rapidly step up to the position occupied by CS. After nine seconds have elapsed, magnet DM3 energizes in a circuit including wiper 3 of US, and when US has taken a further step, falls back to drive TS one step. The disc on the shaft of US displays numerals 1 to 9 in recurring series at an observation aperture, and the disc of TS displays numerals 1 to 49. An alternative indicating arrangement comprises lamps wired to additional contact banks of US, TS, the circuits of the lamps being preferably completed over key SK. Operator's listening and speaking arrangements ; recording and timing various operations. The secondary of the repeating coil RP is connected across the input terminals 89, 90 of the amplifier, the output terminals 91, 92 being connected to operators head-set over contacts of key K. If the operator desires to speak to a subscriber, he will operate K so that the low resistance upper winding of TK is placed in parallel with its high resistance lower winding, whereby TA is permitted to energize and operate TR which in conjunction with key K connects the operator's set directly to conductors 2, 3. When the calling party dials, the opening of the loop discharges condenser CN over 30, CX (i and iii) so that the armature of CX swings back to open the circuits of CX(iv) and XA. Slow release relay XB holds during impulsing, and CX holds over 27, CX(ii), 32, 25, 4 while the loop is open, during which time, pen register PR is operated over 33, 25, 4 to mark a moving tape. When the loop is closed again, charging current for CN flows through CX (i and iii) in the opposite direction and the armature of the relay opens the circuit of PR at 25 and closes its original holding circuit at 26. By observing the moving tape and taking readings on the timing apparatus, the operator can note the time when dialling commences and ends, and he can further note the time at which ringing or busy tone is sent back. When the called party replies, the calling subscriber's meter is operated and the high resistance. relay connected to conductor 16 is shunted by a low resistance to permit relay MD to energize, whereupon tone from TD is connected to operator's set to inform him that metering has taken place. Relay MT pulls up slowly to disconnect the tone lead and light lamp ML, and the operator notes the time at which this operation occurs. Completion of observation; restoration of timing equipment. When the calling party replaces his receiver, TK falls back and the discharge of CN operates CX (i and iii) as before. After an interval XA and XB fall back to disconnect the pen register and at the same time open the holding circuit for CX(ii) and complete a circuit for OX(iv) the armature of which again makes contact at 26 so that XA and XB pull up again in readiness for the next call. The operator presses RK to unlock G and MT and disconnect lamps GL, ML. On the relapse of relay TK, the relays of the timing apparatus fall back and homing circuits for switches CS, US, TS are completed. Faulty train of switches held by operator. Key LK connects ground 61 over conductor 22 to a relay (not shown) which connects an impedance coil across conductors 2, 3.