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 PABX implemented with Uniselectors?
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 Return to top of page · Post #: 1 · Written at 3:00:32 PM on 31 January 2022.
NewVista's avatar
 Location: MilwWI, US
 Member since 10 May 2013
 Member #: 1340
 Postcount: 833

A place I worked in Bris~1967 had around ~100 extensions and I saw them install a "new" PABX that seemed to have only Uniselectors as the active elements (rather than the expected Strowger stepping devices.)

I'm wondering was I seeing right? Was this a common practice? Was it a commercial product, or a home-brew by a local entrepreneur?


 
 Return to top of page · Post #: 2 · Written at 7:44:36 PM on 31 January 2022.
BringBackTheValve's Gravatar
 Location: Linton, VIC
 Member since 30 December 2016
 Member #: 2028
 Postcount: 337

 
 Return to top of page · Post #: 3 · Written at 1:30:01 PM on 1 February 2022.
NewVista's avatar
 Location: MilwWI, US
 Member since 10 May 2013
 Member #: 1340
 Postcount: 833

That's a good link that, coincidently, had more info on the W.E.#1-ESS that I'd been brushing up on elsewhere on the web!


 
 Return to top of page · Post #: 4 · Written at 12:43:49 PM on 12 February 2022.
Relayautomatic's avatar
 Location: Canberra, ACT
 Member since 24 April 2012
 Member #: 1136
 Postcount: 151

No NewVista your memory is not failing you. There were uniselector based PAX and PABX units installed worldwide from the 1920s to the late 1970s. They were more 'common' in PAX units up to 100 lines but ten to 50 lines was the usual size.

In the UK and also Australia there was a major company 'Telephone Rentals - TR' that both sold and rented business phone systems that used uniselectors. The key selling points were that these systems were cheaper than a PABX from the British BPO or Australian PMG (government owned telcos) and they were not connected to the public network so staff could not make outside calls.

The manufacturers that I have details of were Ericsson/ETL, (British) GEC and STC. In the 1920s Western Electric in the USA did make a PAX that was supposedly based on their 'Rotary' switch but was actually a form of uniselector (i.e. self driven by solenoid). Strowger/Automatic Electric (USA) made a range of uniselector based PAX and RAX units used in the US and elsewhere including Australia. In particular AE developed a special uniselector (called a Rotary Relay) PAX for the US Navy to be used on ships at sea. These could cope with the vibration/movement of the ship in rough seas and also the shock of naval guns being fired.


 
 Return to top of page · Post #: 5 · Written at 5:49:45 AM on 15 February 2022.
NewVista's avatar
 Location: MilwWI, US
 Member since 10 May 2013
 Member #: 1340
 Postcount: 833

R.A. - Interesting that these were relatively common around the world. At that time I had actually purchased uniselectors at Surplus store very cheaply and tried making an EM 'one-armed-bandit' with 3 rows of lights, wiring the selectors to scan & stop and their other rows for payout verification. The project stalled, too difficult, not having a workshop.

Coincidentally, another place I worked in Bris. in the late 70's must have had a few hundred extensions, and lots of money, and I saw them upgrading to a 'state-of-the-art' STC(?) PABX in a nice 6'-high blue cabinet. From what I could see inside, it had electronic circuit cards and Reed-relay crosspoint frames! Maybe stored-programme-microprocessor(?), and fully certified to access the outside public network!


 
 Return to top of page · Post #: 6 · Written at 11:19:18 AM on 17 February 2022.
Relayautomatic's avatar
 Location: Canberra, ACT
 Member since 24 April 2012
 Member #: 1136
 Postcount: 151

For New Vista (or anybody else who is interested) I have collected links to various PAX and PABX using uniselectors and also just relays for switching.

Although Strowger two-motion selectors (also known as Step-by-Step switches) were more common for larger switches/exchanges there were several other electro-mechanical system used worldwide. Eventually 'Crossbar' replaced most of these and then hybrid electronic and reed relay switches became the standard before fully computerised digital 'packet switching' displaced analogue telephone systems from the 1990s onwards.

A couple of the links give details of the STC developed TXE system which itself was a derivative of the first electronic computer 'Colossus' developed in WWII to find the key patterns for the German teleprinter encryption devices. It is likely that the '"PABX in a nice 6'-high blue cabinet" you remember was a TXE unit.

The humble uniselector was in fact a very versatile device and was used in a number of calculating applications including the first electro-mechanical totaliser designed by British Ericsson for use at racecourses. Back in WWII the Japanese used an encrypt/decrypt machine similar in concept to the German 'Enigma' device and this used sets of three or five uniselectors instead of mechanical rotors. The US finally cracked this coding scheme with considerable (unacknowledged) assistance from Australian military personnel.


https://telephonecollecting.org/Bobs%20phones/Pages/STCAustralia/STC%20Australia.htm

https://www.vintagephones.com.au/Pages/STCAustralia/STC%20Australia.htm

https://www.lightstraw.uk/ate/stc/telephone1.html

https://www.britishtelephones.com/ericsson/pax10.htm

https://www.britishtelephones.com/siemensb/pax21.htm

https://www.britishtelephones.com/ericsson/paxover.htm

https://www.britishtelephones.com/ericsson/bulletin/7_20.htm

https://www.britishtelephones.com/ericsson/pax50.htm

https://www.britishtelephones.com/ericsson/pax5040.htm

https://www.britishtelephones.com/atm/t4353.htm

https://www.britishtelephones.com/ericsson/menupabx.htm

https://www.britishtelephones.com/ericsson/bulletin/40_3.htm

https://www.britishtelephones.com/gec/5000.htm

https://www.britishtelephones.com/gec/journal/currentcomments/1932_vol2_118.pdf

https://www.britishtelephones.com/histtr.htm

https://en.wikipedia.org/wiki/TXE

http://www.coxhill.com/trlhistory/media/Telecommmunication%20Journal...

http://www.samhallas.co.uk/repository/others.htm

http://www.samhallas.co.uk/repository/documents/txe4_century.pdf

https://ur.booksc.eu/book/45701739/f8823f


 
 Return to top of page · Post #: 7 · Written at 2:57:23 PM on 18 February 2022.
NewVista's avatar
 Location: MilwWI, US
 Member since 10 May 2013
 Member #: 1340
 Postcount: 833

Interesting to learn here the derivation of the name STC being by changing Western Electric to Standard Electric in England (just like it was changed to Northern Electric in Canada.) Would explain how I once noted, while touring the Mormon temple at Kangaroo Pt Brisbane, an iconic Deco Western Electric ribbon microphone that was branded STC! Apparently after the post-war court-appointed restrictions placed on AT&T, manufacturing rights for some non-telephone products fell to STC - and Altec - who also could make the same mike!

Seems it's hard to find more pictures/details of the Ericsson electro-mechanical Totalisator installed at some English racetracks.


 
 Return to top of page · Post #: 8 · Written at 11:02:43 PM on 20 February 2022.
Relayautomatic's avatar
 Location: Canberra, ACT
 Member since 24 April 2012
 Member #: 1136
 Postcount: 151

Thanks for correcting my spelling of 'Totalisator'; you can see that I am not a fan of horse racing. There was a description of the device in the LME Review Vol VIII, 1931 but I cannot locate a copy online. There is some information in this link:

https://www.ericsson.com/en/about-us/history/company/the-consequences-of-expansion/ericsson-and-the-great-depression

In 1925 AT&T which controlled the Bell Telephone Company and Western Electric, sold off most of its non US assets/companies to what became IT&T (International Telephone & Telegraph). Most of these were renamed so British Western Electric became Standard Telephones & Cables. AT&T operated only in the Americas and IT&T operated everywhere else. AT&T/Western Electric and IT&T/STC continued to swap/share patents and other designs so often STC made equipment had WE part numbers starting "W 40xx"

Getting back to Ericsson PAX units, see:

https://www.telephonecollectors.info/index.php/browse/bc-switching-library/all-bc-library-topics/other-makers/13087-ericsson-sep46ca-priv...


 
 Return to top of page · Post #: 9 · Written at 2:27:13 PM on 21 February 2022.
NewVista's avatar
 Location: MilwWI, US
 Member since 10 May 2013
 Member #: 1340
 Postcount: 833

Oops, I didn't mean the bolding as a spelling 'correction' as I understand both spellings are used here & there and at different times, it's just that I like the word and that it's an Aust invention, thus bolding. Great English Ericsson catalogue there, clearly showing uniselectors in 50 line extensible units. I believe now the place I was at in 1967 was closer to 50 lines than 100.


 
 Return to top of page · Post #: 10 · Written at 4:12:45 PM on 22 February 2022.
NewVista's avatar
 Location: MilwWI, US
 Member since 10 May 2013
 Member #: 1340
 Postcount: 833

I believe this video here shows rare view of the Ericsson Tote operating in 1931, and a tech replacing a modular adding unit on the fly (no need to turn off the power to avoid blowing any transistorsSmile)

https://www.youtube.com/watch?v=F5rjvGM8GVo


 
 Return to top of page · Post #: 11 · Written at 5:38:51 PM on 22 February 2022.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6338

That video is a great find. Hotswapping indeed.

Not sure about the £10/2/6 bets being asked for at the window, given that the stake unit is shown as being 2 shillings.


 
 Return to top of page · Post #: 12 · Written at 6:08:57 PM on 23 February 2022.
Relayautomatic's avatar
 Location: Canberra, ACT
 Member since 24 April 2012
 Member #: 1136
 Postcount: 151

Very interesting video that I had not seen before. I liked the views of the uniselectors working away but I reckon that the 'hot swap' feature would have come in handy as those unis would have would have worn out quite quickly.


 
 Return to top of page · Post #: 13 · Written at 8:06:57 PM on 23 February 2022.
BringBackTheValve's Gravatar
 Location: Linton, VIC
 Member since 30 December 2016
 Member #: 2028
 Postcount: 337

I have a vivid memory of an inner city exchange in Melbourne in 1983 when I was employed by Telecom BBI (Broad Band Installation) section.

While installing Ericson PCM equipment, a maintenance tech was busy out the back of the exchange amongst a pile of decommissioned electromechanical switching gear. I said g'day , introduced myself and asked what he wad doing. He was pulling switches apart with pliers and with great enthusiasm showed me a small jar containing contacts, much like the 'points' in car distributors way back then. He estimated he had five ounces of the valuable metal.

I can't remember if the contacts were platinum or tungsten, but a few days later he received $140 for the jar from the scrap metal dealer.

Anyone remember what metal the contacts were made from?

Platinum is worth $1533.80 per ounce at the moment, that's over seven and a half grand for that little jar today.


 
 Return to top of page · Post #: 14 · Written at 10:56:43 PM on 23 February 2022.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6338

those unis would have would have worn out quite quickly

You bet! Smile


 
 Return to top of page · Post #: 15 · Written at 12:29:39 AM on 26 February 2022.
NewVista's avatar
 Location: MilwWI, US
 Member since 10 May 2013
 Member #: 1340
 Postcount: 833

With the Great Depression taking hold, Ericsson would turn to alternative enterprises, and what better than horse racing which boomed around the world right through the 1930s (gambling being a recession-proof business.) Brisbane had two racecourses side by side, and not far away a Pacer track, then a Dog track (do you think that city might have had a gambling problemWink)


 
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