AT & TCo Standard SECTON 518-010-108 ssue 5, November 1980 COMMON AUDBLE SGNALNG KEY TELEPHONE SYSTEMS 1. GENEAL 1.01 This section provides a general description of common audible signaling arrangements, especially those using diode matrix or signal control relays. t also describes the need and use of the 14lA protector and 840A diode assembly. 1.02 This section is reissued to: Add information that the 446F diode is replaced by the 533F diode qr equivale~t Correct minor errors in text Change Fig. 7 to add designation on 840A diode. 1.03 Common audible signaling provides for: Signaling one station from more than one CO, Centrex, PBX, or intercom line Signaling more than one station from one CO, Centrex, PBX, or intercom line Signaling combinations of the previous arrangements (with these combinations, a diode matrix or signal control relay is required). 1.04 Common audible signaling arrangements, which utilize a local frequency generator (110 volts, 30 Hz) for operating ringers, can be subjected to voltage spikes of sufficient amplitude to damage key telephone units (KTUs) and/or blow fuses. Depending on the phase o{ the current through the ringer when the current is interrupted, voltage spikes of either polarity can appear on the C lead. 1.05 To protect against these ringer transients, a 141A protector is connected between the B1 and 1 terminals in the station cable to each ringer. 2. Note: The 141A protector is not required if a 400G or 400H KTU is used in the line circuit. COMMON AUDBLE SGNALNG CCUTS-OPEATON 2.01 A simplified schematic of one audible signal operated from two lines is shown in Fig. 1. A call on line 1 operates relay in line circuit 1 causing contact to make. The ac sig-nal is applied through diode CL Diode Cl allows the positive cqmponents of the ac signal to operate the common audible signal. Diode C2 isolates line circuit 2 from this signal. A call on line 2 will result in relay in line circuit 2 operating and applying the ac signal via C2. 2.02 f the station audible signal (fig. 1) will be rung only from lines 1 and 2, and if these lines will not ring any other station, the diodes and diode matrix are not required. 2.03 Common inging Lead: A simplified schematic of one line operating two-station audible signals is shown in Fig. 2. A call on line 1 operates relay, causing contact to make. The ac signal is applied through diodes C1 and C2. The positive components of the ac signal operates both station audible signals. 2.04 f ito other line will ring station A or B (Fig. 2), the diodes and matrix are not required. ingers in the stations can be rung directly from tip and ring of the line. 2.05 A simplified schematic of a two line, three-station common audible signaling arrangement is shown in Fig. 3. A call on line 1 results in a signal at stations A and B, but not C since diode C3 blocks the path. A call on line 2 results in a signal at stations B and C, but not ~ This document s either AT&T Proprietary, or WESTEN ELECTC Proprietary r.-ursuant to Judge Greene's Order of August 5, 1983, beginmng on January 1, 1984, AT&T will cease to use "Sell" and the Bell symbol, w1th the e ceptions as set forth tn that Order, Pursuant thereto. any reference to "BELL" and/or the BELL symbol in this document is heraby deleted and "expunged". Printed in U.S.A. Page 1
SECTON 51 8-0 1 0-1 08 A due to diode C2. Station B is common to lines 1 and 2. Stations A and B are common to line 1. Stations B and C are common to line 2. 3. COMMON AUDBLE SGNALNG APPLTONS 3.01 An example of a diode matrix installation is shown in Fig. 4. To the left is a schematic representation of the 1A1 matrix block. At the right, 533F diodes or equivalent, are connected so their arrows point towards the station audible signals, permitting five signaling leads to control six audible signals. The block could also be wired to permit six signaling leads to control five audible signals by connecting the signaling leads at the left side (A-F) and the audible signals at the top (1-5). For this configuration all diodes must be connected so their arrows point.toward the_audible signals. All line circuits connected to a diode matrix must be supplied from the same ringing supply and interrupter contact. 3.02 A strap is used to connect a signaling lead to an audible signal if neither is common to any other signaling lead or audible signal. An example of this is the strap between signaling lead 5(J and audible signal F (Fig. 4). 3.03 Diode control limits the type of audible signal to either all ringers or all ac buzzers (do not mix). To avoid diode failure, never use de buzzers. When ringers are used, the ringing capacitor of each station should be disconnected and bypassed and the red ringer lead should be connected to the diode matrix. A positive component results after an ac signal has passed through a diode in the direction of the "arrow." This positive component cannot pass through a diode against the arrow. On this principle a diode matrix separates audible signals and signaling leads. ALL DODES AND NGES (F USED) MUST BE POLAZED N THE SAME DECTON. 3.04 The matrix in Fig. 4 1s arranged so that: LL ON LNE 1* 2 3 4 5* STATON(S) SGNALED B A, B, and C A, C, and D A, C, and E F *Signaling leads 1 and 5, corresponding to lines 1 and 5, are not common signaling leads since they each control only one audible signal. 3.05 For a detailed description of the 1A1 matrix blocks, see Section 461-620-100. 3.06 Section 518-215-403 provides functional schematics of the 402A and 404A (diode matrix) KTUs. 3.07. Common audible signaling can also be accomplished with the use of signal control relays via a diode matrix. The same principles apply. nstead of diodes, relay contacts connect the ringing leads to the proper ringers. Section 518-310-401 provides various connections using the 227B KTU as a common audible. signaling control. 3.08 To provide common audible signaling on large key systems, a matrix arrangement can be provided by using 66B- or 66M-type connecting blocks and 840A diodes. The 840A diode is an assembly consisting of a diode connected to two spring contacts encapsulated in a clear plastic housing. The 840A diode is inserted on adjacent terminals of the 66-type connecting blocks. 3.09 A typical common audible signaling arrangement using a 66B-type connecting block, and 840A diodes for signaling one common audible signal from three CO/PBX lines in addition to audible signals at the individual stations, is shown in Fig. 6. efer to Fig. 7 for the polarity designation of the 840A diode. 4. 14 1 A POTECTO 4.01 The 141A protector (Fig. 5 l consists of a 68,000 ohm, 1/2-watt resistor in a blue molded assembly. The dimensions of the protector are 6/10-inch by 112-inch by 3/10-inch, and it is designed to be installed on 66-type connecting blocks having quick-connect terminals. Page 2
SS 5, SECTON 518-01 0-1 08 4.02 The 141A protector is inserted between the Bl and l terminals in the station cut-down field (Blue Field) without affecting the cut-down multiple. See Fig. 1, 2, and 3. 4.03 For key telephone system (KTS) installations, every station served by a local frequency generator except those using 400G and 400H KTU s. should be protected by 141A protectors. At existing installations, protectors should be installed for each station (served by a local frequency generator) during routine servicing of the installation. co [ l.ne T l.ne CCUT * C O PAT OF DODE MATX CF,_,' \ ' w FG(81)1 l l TO GD Fllr== i 41A POTECTO STATON AUDBLE SGNAl. F1 O FN AC SGNAL SUPPLY rg TO GD co l.ne Z T FC O C2 l.ne CCUT 2 * ELAY DESGNATON WLL VAY DEPENDNG ON THE TYPE OF LNE CCUT USED Fig. 1-Simplified Schematic of Two lines and One Audible Signal Page 3
SECTON 518-01 0-1 08 STATON A AUD18L.E SGNAL. STATON 8 AUD81.E SGNAl. j AG (81) A A G (81 [ 141A POTECTOS co.ne l r.ne CCUT * '\!\; C O TO GD +-- C {\_{\_ \ ' e,., PAT OF DODE MATX C2 --TO GD A O AN AC SGNAL. SUPP.Y ~G TO GD t E.AY DESGNATON Wll.l. VAY DEPENDNG ON THE TYPE OF.NE CCUT USED Fig. 2-Simplified Schematic of One Line and Two Audible Signals Page 4
SS S, SECTON S 1 8-01 0-1 08 i STATON A STATON B STATON C AUDBLE AUDBLE AUDBLE SGNA-L Sl GNAL SGNAL!,.,,. v G!Bll l l G (B) l G; 811 141A ~OTECTOS TO GD TO GD TO GO 141A P<OTEC70 T LNE CCUT co [ LNE C O C tc2 C3 C4 * ~AT OF DODE MATX AC n O FN SGNAL G SUPPLY TO GD T * co [ LNE 2. C O LNE CCUT 2. * ELAY DESGNATON WLL VAY DEPENDNG ON THE TY~E OF CCUT USED. Fig. 3-Simplified Schematic of Two Lines and Three Audible Signals Page S
SECTON 518-01 0.108 SGNALNG.EAOS [ FOM.NE CCUTS 2--- C 0111 SGNA.NG.EAOS FOM.N CCUTS z ll<: 0111 3 C O 4 C O 5 C O Cllll C Z CS A l C4 CS 1111 C c 1111 STATON AUO. SGNALS 0 1111 Clllt CO E l STAP -: Bl F 1111 '--' TO STATONS - A,B,C,O,E, AND F Fig. 4-1 A 1 Matrix Block Appli~ation 'ow '
SS 5, SECTON 518-010-108 tpa6237.' COYt:lt SPNG CONTACT Fig. 5-141 A Protector TO LNE SGNALNG LEADS N1 ~- -P~T-;;F-;S;-T;E~O; ~K--:--i N2..:.:.:.:=+------11-o---9----0 STAP TO COrlriON. AUDBLE 6-----o--++-- SGNAL FO STAP STATON A, B AND C N3 STA STA STA A B C TO STATON AUDBLE SGNAL Fig. 6-Typical Common Audible Signaling Arrangement on 66-Type Connecting Block With 840A Diode Page 7
SECTON S 18-010-1 08 ] 00 ~OL1\ TY OESCNATON Fig. 7-840A Diocle4 Page 8 8 Pages