[VoIP] Spotted On Ebay

Thu Feb 7 10:38:05 CST 2008

Two volumes of Atkinson's #Telephony' for £50.00 (US$97.00 for out Colonial friends :-)  ) -  you obviously didn't buy them new as I did !  It took two years to pay for them at £x. xs  xd per week from my wages!   They probably cost that much 50 years ago when I bought mine !

A bargain at modern day prices. Mind you I bought a "Vol 2" for some-one the other day for £6.76  -  and the postage was £7.00  :-(

Ian J

  ----- Original Message ----- 
  From: windmill 
  To: Ian Jolly ; Voice Over IP Tandem for Analog Switches 
  Sent: Thursday, February 07, 2008 12:22 PM
  Subject: Re: [VoIP] Spotted On Ebay

  No book is worth that amount of money to me! I thought £30+ for a 1928 book about London Underground and £40+ for an IRSE  reference work on British Railway Signalling were close to my limits when i bought them on Ebay. Interestingly I saw someone asking a ridiculous starting price of £50+ for volumes 1&2 of Atkinson's Telephony recently and they were late editions.

  Brian

  Ian Jolly wrote: 
Forgot to mention - there's a good book on Strowger systems at 
http://tinyurl.com/2wbfzt     I've got my copy!  It is of use to me as I 
have couple of final selectors (connectors) from the UK's first public auto 
exchange which the book describes in detail together with all its large pull 
out circuit diagrams.  When I get time I hope to build a small demo switch 
incorporating the selectors/s.

I think this book is about the same date as the one Mark is using !

Ian J

----- Original Message ----- 
From: "Ian Jolly" <ian at uax.org.uk>
To: "Voice Over IP Tandem for Analog Switches" <voip at ckts.info>
Sent: Thursday, February 07, 2008 9:13 AM
Subject: Re: [VoIP] Spotted On Ebay

  I've replied at length to Mark on this one to save clogging the list up 
with
'non-CNET' info. Also pointed him in the direction of  the bible as used 
for
UK systems - Atkinson's 'Telephony' and its predecessor - by Herbert &
Procter which covers most UK manufactured systems.

Ian Jolly

----- Original Message ----- 
From: "Mad Mark" <madmanmarkau at hotmail.com>
To: "Voice Over IP Tandem for Analog Switches" <voip at ckts.info>
Sent: Thursday, February 07, 2008 3:01 AM
Subject: Re: [VoIP] Spotted On Ebay

    I won the items, and they should be arriving in a few days, if all goes
well. Sounds like that S17 is the perfect novelty piece for a display. 
Now
I understand why someone said it was rather unusual.

Anyway, I'm going to copy/paste an E-Mail I sent to Ian and John. Perhaps
you can help me too.

*** Begin message ***

I’ve been reading up on EM
switching gear from the Automatic Telephony book by Arthur Bessey Smith
and
Wilson Lee Campbell, and have a couple of questions about the line and
cut-off
relays when using a line finder.

First, can you confirm my
understanding of this. When the customer goes off-hook, the Line-Relay
(LR)
actuates, connecting the motor-magnet (MM) of the line-finder to the
private
wiper (PW) and off into the rest of the exchange. If the PW is grounded 
by
the
rest of the exchange, the current flows via the MM through the PW and to
ground
via the rest of the exchange, advancing the line-finder (because the MM 
is
basically a chopper circuit).

When the wipers rest on an idle
trunk, the PW is no longer grounded, so the MM doesn’t have a ground
connection
for power so can’t actuate. However, the cut-off relay (COR) has enough
current
via the MM to actuate, cutting the customer loop through to the idle
trunk, and
connecting the PW to ground via the LR, busying the trunk circuit. 
Because
the
COR has now actuated, the LR is cut off and slowly releases, being a slow
release relay.

Here’s the part I don’t quite
understand. After the LR has released, it disconnects the ground from the
COR
relay. What is now supplying the ground connection to keep the COR
actuated? Is
it something at the other end of the trunk? Or am I missing something?

The following are assumptions
based on the circuit diagram I have. When the called party disconnects,
the
ground is removed from the Trunk Release line and PW, thus removing 
ground
from
the COR, returning the relay to the normal state and connecting the
customer
line back onto the LR. The LR is getting power because the customers
handset is
still off-hook, so it actuates again, and causes the COR to actuate,
reconnecting the line to the trunk, and cutting power to the LR. The LR
releases AGAIN, causing the COR to release, etc… One huge chopper circuit
is
happening. Or, maybe the trunk circuit sees the momentary ground on the 
PW
and
applies its ground to the PW as if the customer had just picked up their
handset again. I am most probably misunderstanding this greatly, as I don’t
see
this happening as being a good thing.

And I am assuming the connector
switch or some circuit further up the trunk handles all call disconnects…

Also I’m assuming the line-finder
rotates only in one direction and has two sets of wipers, one set coming
into
use at position 0 when the other set (positioned at 180 degrees) leaves
position 24 (or whatever the maximum is) and rotates into dead air. Is
this correct?

Can you give any clarification on
these points?

      Date: Mon, 4 Feb 2008 16:31:39 -0500
From: martin at Princeton.EDU
To: voip at ckts.info
Subject: Re: [VoIP] Spotted On Ebay

Mad Mark wrote:
        Someone on the CNET-UK-I mailing list spotted these items on E-Bay:

130193124276

130193124377

130193124440
          The first appears to be a standard BPO type 1 uniselector.  The third is
a BPO "miniature' uniselector (type 4 if memory serves.)

The second item is rather interesting.  I *think* it's a Siemens
digit/pulse counting switch, developed by them for their number 17
system (the one that used motor uniselectors.)  Unfortunately, from the
pictures it appears to be missing it's wipers, so it's no ore than a
display piece.

S17 was never used in public service in the UK as far as I am aware, but
maybe it was in Oz...  One of the big oil companies, I forget which, had
a big S17 PBX installation in their London office.

Martin
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