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A  Closer  Look  ...
 
» HOW THE TELEPHONE DIAL SYSTEM WORKS «
 
A  DELAY-RELAIS  added  ...



...  to  prevent  contacting  users  while  SSW  Relais  is  in  motion.

The  DIALER'S  PULSE-TIMING  shown  ...
( Diagram  glued  on  its  Back  Side )



THE  DIAGRAM  OF  THE  REVISED  DIAL  SYSTEM  ...



THE  BUILDING  BLOCKS  ( with  the  Diagrams  on  its  Back  Sides )  ...

   

H O W   T H E   E X P E R I M E N T A L   D I A L   S Y S T E M   W O R K S :
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RELAIS (RELAYS) and their associated CONTACTS are shown in the SAME COLOR.

where:   r = "rest"     Contact is closed when the relais is not activated.
         a = "active"   Contact is closed when the relais is activated.

SSW(r12) opens, when the SSW ( = "Schritt-Schalt-Werk" ) reaches POSITION 12.
SSW(r02) opens, when the SSW ( = "Step-Switch-Work" ) is in motion.
SSW(r01) ( with RR(r) & DR(a), the ACTIVE TIME DELAY of DR-Relais )
         ensure that NO USER CONTACT is made when the SSW is in motion.

The DIAGRAM shows an IDLE STATE with USER "3" SELECTED.  To change the user,
first a RESET is necessary.  Pressing ( and releasing ) the RESET Button
activates the RESET-Relais, because SSW(r12) is closed.  With RR(a1) it holds
its own activation and with RR(a2) it starts the PULSAR-Relais.  The PULSAR-
Relais activates with PR(a) the SSW until the SSW reaches position 12 and
opens SSW(r12).  This deactivates the RESET Relais and opens RR(a1) & RR(a2).
This stops the PULSAR Relais.  The RESET Position is found.

Selecting (e.g.) a new USER "6" by DIALING the "6" lets the SSW move 6 steps
to position "6". After a DELAY TIME contact DR(a) connects the USER "6" ...

R E M A R K  (DR) DELAY-RELAIS:  S1 = T1 = ON-Delay;  ( S2 = T2 = OFF-Delay )

See ... "HOW THE PULSAR IS WORKING" ...  in the chapter COUNTERS.

                   Back to the Photo with the Building Blocks ...

IN  A  REAL  R E L A Y  D I A L  S Y S T E M  from  1950  (eg. DEUTSCHE POST)
"SSW"s were connected in a tree-like structure.  When customer A picks up his
hand set, the 1st SSW connects customer A with the  (FERNMELDEAMT  in German)
SWITCHING STATION  and customer A gets a  DIAL TONE.  When  customer A dials,
every digit activates a  SSW in sequence  until the selected  customer  B  is
contacted.  Pulses from the  SWITCHING STATION  activates the  RINGER  in B's
station.  Customer B picks up his hand set and the connection between A and B
is established.  When the conversation is finished,  A and B  hang up and all
SSWs are RESET ...

Have a look at the DEMO-VERSION of a 4x12-Step-SSW ...

   

   The SSW 0/12 Position-Control-Plugs LEFT ... RIGHT the SSW Power-Plugs

                          Historical Remarks ...
impressum:
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© C.HAMANN         http://public.beuth-hochschule.de/~hamann         09/10/11