Patent GB-469184-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/00
Filed: 1936-01-20
Abstract: 469,184. Automatic exchange systems. AUTOMATIC ELECTRIC CO., Ltd., TAYLOR, R., and BAKER, G. T. Jan. 20, 1936, No. 1805. [Class 40 (iv)] In a register-controller of the code translating type, the non-operation in the case of calls from coin-box substations of a relay that is normally energized when the registercontroller is seized, prevents the establishment of certain multi-fee calls and causes a special translation to be sent out in the case of zero calls so that the call goes to a special operator or to the normal operator over a characteristic route. The register-controller is reached over an A-digit switch and has the usual facilities, e.g. the suspension of transmission in the case of calls to call indicator offices until the distant apparatus is ready, forcible release of the register-controller and A-digit switch in the case of premature or incomplete dialling and means for putting the register-controller out of service for testing, traffic registers and supervisory lamps. Specifications 358,043 and 391,151 are referred to. Selecting and setting A-digit switch. Operation of the line relay L, Figs. 1 .. 3, in series with the current limiter BRA is followed by that of A, I, B, C, BB. The switch ADH then hunts under control of K which removes a shunt from the switching relay KR when an idle A-digit switch Figs. 4, 5, (marked by battery over 1A, Y3 in parallel) is reached. Double connections are avoided by making K reverse the current through its upper winding, the arrangement being very similar to that described in Specification 435,411. In the A-digit switch, 1A, which operated initially in the test circuit, is followed by 1C, 1B and is then held over the impulse wire PU. The switch responds to the A-digit in the usual way and hunts by self-interruption under control of H which allows the switching relay HR to pull up when an idle register-controller is reached. 1A, 1B, 1C then fall back. Normal operation of register controller, Figs. 6 .. 9. Impulse relay 2A is followed by relays 2B, 1BA, RS. The remaining digits are recorded on a BC register and numerical registers, the units register acting as digit distributer under control of 2C. The translated and numerical digits are sent in the usual way under control of relay IG, sending switch S, loop and magnet springs 1MP1, IMP2 and stop relay SZ. The interdigital pause is given by stepping the sending switch from position 15 to position 19 by the interrupter. At the end of the transmission of the units digit, CO initiates the release of the A- digit switch, switch ADH and the register controller in which the switches are restored in succession beginning with the sending and sender-control switches and ending with the BC. register. Special treatment of coin-box calls. In this case full earth is connected to the point D from the finder (not shown). RS in the register controller is thus short-circuited via the rectifier MRF in normal calls and directly in the case of zero calls in which the register controller is seized with the + and - wires reversed. As a result, in the case of zero calls, in which 1D and MB are operated to cause the call to be routed to an operator, a different routing number is sent out to give the normal operator an indication of the type of call or to route the call to a special operator. In the case of automatic calls, the establishment of highvalue calls is prevented by the inclusion of bank S5 in the marking circuit for the first translated' digits. A strap is connected between the terminals of S5 corresponding to permitted first digits and the wiper 1d. In case. a prohibited call is attempted the sending switch fails to find a marking and energizes the forced release' relay 1M which causes NU tone to be given from the first code selector.' Double-hunting first code selector. L, A, I, B, C, BB are operated initially and in due course A responds to the first translated digit to raise the switch. The double-hunting arrangement resembles that described in Specification 447,767, the rotary magnet operating in a self interrupting circuit until one of the relays HA, HB (which were energized initially over middle windings and locked subsequently over the test wipers) is released. If both fall back, HA re-operates and the call goes over the upper set of wipers. In all cases, BA pulls up when either HA or HB falls and switches the impulse circuit through. Metering. Supervisory relay D which is polarized by the shunted rectifier MRE initiates the operation of DA, DB by S and Z pulses. During the Z pulse, RG responds a number of times depending on the position of the vertical wiper and gives booster impulses over the private wire. After the Z pulse, DA falls and DB remains locked. If metering is to depend, in some cases, on the level of the second code selector, the upper bank of the first code selector does not give access to separate outlets, the negative terminals being used for the transmission of an appropriate number of metering impulses from the vertical wiper of the second code selector as described in Specification 406,270. Operator hold and re-ringing arrangement. To hold the connection, the operator puts battery on the positive lead to hold I, after L has fallen, in series with rectifiers MRA, MRC which with MRB, MRD effectively shunt RG. Operation of her re-ring key applies reverse battery to the positive wire and RG is then able to respond and connects ringing current to the calling line.