Excellent presentation by H.Bluestein

Great

29:00 I always wondered how the exchange knew you had dialled the last digit and attempt to connect.

to much blablabla

Everything is now Touch Tone but will be moving to VOIP so telephone exchanges will start to disappear.

There was a very short cable from Oaklands Cullybackey to the telephone exchange as the exchange was at the back of Oaklands Cullybackey.

Really great presentation... Would be great to hear a version of this for class 4 and VoIP ! Thank you !

Can finger prints biometric be added to a android device that doesn't have it

I left school in 1973 and went straight into an apprenticeship with Post Office Telephones, the British government owned communications arm of the mail service. While I was there it became British Telecommunications, and then British Telecom. When I joined, all the phones were of similar design to those in the US, and all the telephone exchanges I entered were exclusively Strowger. By this time Crossbar was in evidence, but since exchange building and extensions were done to a 10-year plan, all new equipment in normal exchanges was Strowger, and by that I'm referring to 2000-type 2-motion selectors. However, there were still older exchange equipment and that included 1000-type two motion selectors, which were identical to the 2-motion selectors you were showing, with the curved front to the relay cover. The 2000-type had a neater squared off cover with a flat front that made for a cleaner looking rack. I loved to work on those selectors. Every different type of 2-motion selector in the exchange had a type number, and there was a sheaf of cards in a card file that gave you all the timings for the mechanical operations, and the spring tensions for the relays. I must have been a bit weird, because I seemed to be the only one in the exchange who was prepared to take a selector that had logged a fault out of the rack and take it to the bench and completely check it over, replacing parts where needed. It was not unusual for the vertical pawl to wear beyond the point where it could be adjusted within the limits required, and would need to be stripped down, and it was common for relays to go out of spec causing timing issues. When you knew what to do, it was easy to get the equipment to work perfectly. Sadly, the onward march of technology meant these wonderful pieces of electro-mechanical engineering were on their way out. I came back to that same exchange on a trip organised by the college I was doing my coursework with for my apprenticeship, to see the Trunk Switching Centre. The city were were in, Bristol, was the biggest city in the South West of England, so it was inevitable that there would be a trunk switching centre there. It was Crossbar, and it was a bit of a showpiece. They had a big board with a graphical demonstration of the sequence of a connection as it went through the switching centre. It took about 20 minutes to half an hour to explain it, with lights flashing on and off as the connection was dealt with. Then they showed how long it took to make the connection in real time and it was extremely quick. I couldn't get my head around it, because I could only think in terms of a dialled number making the progress through the exchange. I understood it later though. I know I've written quite a lot, but one difference with the exchanges in the UK was the Linefinder. In the UK, this was implemented as a Uniselector. I'm sure you're familiar with these but, if not, they are implemented as a semi-circular multi-bank set of contacts, with multiple double-ended contact wipers on a single shaft wiping across them, so the banks were swept twice per revolution, and the wipers only wiped in one direction. By using these, I guess they kept costs down, it was also possible to hunt across multiple-hundreds of incoming connections with a single line finder, as I believe there were something like 50 steps across the bank, and there could be six or more sets of wipers. One other difference between our relative systems, despite the similarities, was that all our calls were metered (except emergency) so metering was well and truly implemented in all exchange circuits, and the type of call made determined the timing between meter pulses that made the meter count. The meters were read by a special camera with a frame that fitted the rack and allowed the photograph to be taken without external light interference, and controlled internal lighting. The values on each meter could be compared with the last meter reading taken, but I believe automatic character recognition was used very soon, and computers soon took over the calculation. Of course, by the time System X came in (our version of Ericsson's electronic exchanges), metering of calls was imbedded in the software and there was no need for meters.

Yes

I just happened to come across this video. I retired from AT&T in 2004 after 31 years and am familiar with a lot of the equipment explained in the video. My experience with a cutover was when the Prospect CO in Portland, Oregon, cut to the last #1 ESS before the #1A ESS machines were the only version of the #1 ESS machines were installed. There is nothing in your video about the difference between a #3, #1 and #1A ESS machines. And I think there were a couple of #2B ESS machines in service in smaller COs. (I think Umatilla and Woodburn, Oregon, COs were served by those machines.) When we did the cutover we used electric shears to cut the jumpers at the Bay and Switch on the MDF and spent the next couple of days pulling out the old wire for recycling. There were a few circuits left working on the old MDF we had to identify. Worst yet, the Generator block was on the top of the frame and I don't know how many times I got shocked in the armpit as we pulled jumpers to trace where they were connected to. As far as the #5 Crossbar there were 3 frames instead of the IDF and MDF of the SXS offices. There was the Number Group Frame to identify the number of the end user to ring the correct number, the Translator Frame to provide Automatic Number Identification (ANI) and the MDF. And for SXS offices prior to ANI, an operator would come on the line on DDD calls and ask, 'Your number, please', to record the calling number for Automated Message Accounting (AMA). Once AMA was implemented in an office there was no need for an operator to ask for the calling number. However, customers in offices without AMA and those on 4-, 8-, 10- or 12- party lines would require an operator to ask for the calling number. But customers served by a Type C Central Office would dial more than 1+ for DDD calls. Customers served by those offices would dial an access code generally 1 plus the position on their party line.

Tks for sharing in this video !! IT called me many memories !!

Good morning.... I think its missing a system in this unit that existed between the Strowger and Crossbar ... I used to work to a company called Plessey from Portugal and we had a system PABX 4/20/3 which worked with a very reliable tec that was called UNISELECTOR. Such system was used as well in the PAX ( which only had extensions without PTT lines). Not shure is this developement was only done by Plessey Portugal or if it was developed with or by Plessey UK because the portuguese branch had a high independence. I think it was worth mention. The Uniselector system worked like a "human hand opening and closing for each cicle-number"; By the way the Plessey Xbar system 5005, made in Portugal was only sucessfull made by the portuguese factory and the UK and brasilien factory for some reason were not able to produce the system without bugs. Portuguese team was sent to Brasil to try to sort problems and Plessey which at the time had almost the exclusive supply to Brasil, passed by the shame of seeing its publics switch beeing desmantled and uninstalled due to that bugs ( portuguese team was not able to sort the quality problems ) and be replaced if my mind is remembering correctly, by NEC and Ericson. In Angola the XBar 5005 and the Strowger systems were used up to the nineties. In fact Huambo, Benguela (Strowger) , Cabinda, Malange, Lubango, Namibe (XBar 5005) were the reason why, during the war such towns never lost the phone comunications as the angolan techniciens were able to repair everything producing all components locally ( mainly strogwer ). After the replacement by electronic units such capacity was lost as all the technoogly became "boards and software and licences.

It really depends on the equipment whether you can still use a Dial phone. My Comcast box can ring a rotary phone but cannot distinguish pulse dialing. The Vonage box I had could distinguish dialing but could not ring if I remember right. The Xlink Bluetooth gateway I have now does everything.

The terminologies of tipping ring has even existed outside of the telephone system into the audio world as TRS connectors are tip ring sleeve. And that is the standard is the standard indication of something that's balanced versus unbalanced TS and a 1/4" jack.

Hi Ken! Another ex-dormphone person (John McNamara) here. Great talk; glad to see that you are still "on the right side of the grass, although you have copied my hair style. 🙂

Before computer switches there was step-by-step and Number 5 Crossbar. When Touchtone came along, step-by-step was S-L-O-W but Crossbar kept up with the tone dialing. Step-by-step was awful in General Telephone service areas.

My first job was on telephone exchange construction for plessey telecom in the 70s working on Stranger then crossing bar which had very heavy racks to stand up then System X i did everything from helping to Mark the floor out for the Positioning of the racks, and unloading them of the lorry hanging select Switches and adjust the wipers to the banks to gun raping cables to IDF and MDF one of the biggest mistakes was when someone Decided to make the internal cables to plug directly into the racks, so they all came with plugs at Each end but the were miles too long and we had no way of cutting and reaching the plugs so all the slack was Coiled up onto the grid mesh Which started to sag with the weight .I don’t no if it was ever sorted out because I left to start working for the GPO I am now retired after 40y ending it at the other end of the network has a pole tester with openreach one thing I don’t miss now is following routes of poles across farmland in the winter carrying Ladders on my shoulder

Working for Western Electric way back when, we removed a monkey on a stick switching system in Pittsburgh area, and began the instal of the first , ESS , Electronic Switching System in Pittsburgh.

Make a video of other countries phone exchanges

I noticed you included a video from The Connections Museum in Tukwila, WA. It's quite a wild place--it's still a working telephone switching center but obviously such facilities need only a fraction of the space it once did. The rest of it is stuffed with unique museum pieces--working Strowger, Panel, #1 and #5 XB, and even a 3ESS. I think the Panel and 3ESS installations are the only remaining working examples of either in the entire world. The only downside is they have extremely limited visiting hours--just a few hours on Sundays. But if you're ever in the Seattle area on a Sunday it's worth a look!

i worked in a no. 1 xbar tandem, cama. tsp switch-had trouble recorder, and paper tape ama-used for local tamdem-we had 3 of these-2 only had tandem, cama.

With seeing this video again, I am reminded about my working in Automatic Electric, having a "cross-point" system. which I believe was their name for their version of the crossbar. Technical differences between the two, I don't remember.

Interesting video, one of the best of its type. Thank you.

They did recycle the cables western had their own foundry the old cable came in huge loads and as I recall they melted the lot and the copper was separated form the insulation in the melt. ATT has hundreds of videos of all this stuff on their old ATT history website, so I have seen the footage of this and they bragged about recycling at least 50 years ago. They used so much copper that it would be like burning pallets of hundred dollar bills to throw away the cable from a central office, even when copper was cheap, the mining of it was far harder than just melting some truckloads and trainloads of old cables.

My Grandfather worked for Bell Labs and invented the first automatic billing system for long distance. Before that, the operator had to write down all your call times on a little notebook she had. Presumably that got entered into the billing computers later. But my Grandpa fixed it so the operators could ignore the call once it's connected and no longer had to note when it disconnected and write down the time. He also suggested "push button dialing" but was told it was impossible, and a ridiculous idea. He also was sent to California for 4 years during the war and we found out after he died he had worked on the bomb that whole time.

What do they do with old cables? Good question, any old cables which were cut dead, were collected and sent to Western Electric and the copper was recycled. Even back in the 50s and 60s copper was expensive. This was also true for any scrap copper from the old switch which was cut dead.

I can remember growing up seeing local manual switching in both magneto-local battery and common battery, with the power source at the central office. Local battery arrangement was two or more dry cell batteries in the subscriber's sets for the talking current and a hand-cranked magneto-generator to produce the ringing current. The user on the LB can call another number that shared the same party line by cranking the ringing code(i.e. one long two short)of their party being called. No operator's action is needed.

At about 1:09:00, he mentions the 491 exchange, in Cambridge, MA. I was familiar w/ it because it served a lot of the payphones, there (which was true well into the 90s). So, w/ his mention that it was originally a #1XB, I'd assume that they were once pre-pay, on ground-start lines (from a mention in one of Evan Doorbell's programs).

4127&4879

The Mendel part is completely wrong. Pea color and pod colour are independent traits. Talking about 10 "generations" is also completely wrong. It should be growing 10 offspring plants from a yellow pea plant to see if there is any offspring plant with green peas. In that case, the mother plant had to be heterozygous. However, Fisher could not know if Mendel grew exactly 10 offspring plants; it all depended on Fisher's reconstruction of Mendel's experiments. Mendel's paper was a lecture intended for an audience, not a scientific paper reporting all complications. Mendel had much more data than he presented. Since Fisher (1936), many papers on this topic have been published, including the book "Ending the Mendel-Fisher Controversy". Strong accusations like scientific misconduct need strong evidence and a good understanding of the subject.

Great and interesting video. Good to see ol' Stapleton.

lol sextant... a lot of military aircrafts like bombers have a backup star tracking system. u can get a gps "defender" off of aliexprez for 3$ now day shipped to your door... and the signal is so dirty it messes up multiple systems... i imagine these are being strapped to cheap non gps equipped drones and being used to imobilize and then crash into much more expensive drones in ukraine. there are some clips where it looks like this is whats going on... with all these airtag stalking cases, i feel like we need to update and decriminalize our fcc rules so we could better enforce them by regulating them legally... the devices are going to continue to come in but if theyre 1-2 watt systems with 5-10 foot range with narrow band activity.... seems like a better tradeoff than just going for deterrence... too hard to regulate honestly. just like how those rf radio transmitters dont need a licence under fcc rules for ur car if theyre under a certian wattage

15:48 the cavity magnetron did not raise the frequency of operation it increased the power output at this frequency.

12:16 bandwidth of 10cm ?

12:33 the magnet applies heat?

Get a 20 year old to help the process next time. You built it, we grew up on it. The echo and audio could have been easily fixed

An update on my comment is that the Spanish and NZ exchanges seem to made by Ericsson. The switching was done with uniselectors. The rest was done with relays.

Very interesting. I have worked on UK Strowger and later Crossbar exchanges. I never knew about Panel exchanges as Britain never used them. They used a thing called Directory Strowger on large cities. It had the same idea as Panel switches. They used the first 3 digits to be translated to reach the end exchange and 4 digits to operate on strowger switches. I know that few if any other country used this system. As you said, Sweden designed Crossbar systems and other countries took it up. Other countries took up a Panel system that from the videos I can see are not exactly the same as the Bell system. The videos have Spanish subtitles and have different designs. From the comments, countries like New Zealand used the same design. The UK used two quite different Crossbar designs from different manufacturers, not like the US designs.

i.3.4

Great job Barry! ❤

Hello. I would like to know more information about be jp

So Strowger was a physically lazy but mentally active individual. He would have made a good programmer.

Can you please explain the Quantum Dot tech and Mainframe codes? Little bit curious about it.

In Australia a JP cannot conduct marriages. It has to be a marriage celebrant who is required to do cert 4 in celebrancy

Nice one. Could you share the presentation in blog or as a document?

why aren't we converting decaying nuclear waste into usable energy ?

So good. One minor negative observation: Non baseball analysts: The analytics has led to harder throwing pitchers w/ movement, but the impact of guys who change speeds has been been forgotten. Guys who can change speeds effectively last longer. This impacts the innings he can eat up, which has an impact on the cost structure for each team. Pitchers do not last as long while salaries are escalating. More questions: 2. What is a high pressure moment? 3. Do they understand the minor league testing grounds? 4. Do they understand the need to have a mix of small ball & sluggers in a line up? (line up balance). 5. Do they understand command vs movement "strategy"? (The count is 0-2 a pitcher is not going to throw a strike etc).

Awesome Warren Spahn reference. I looked up Warren Spahn and now I am a fan. What a great discussion. Lecture was interesting too, and funny but smart questions.

@ 43:51 Like Rabi himself Edward Teller emigrated to the States. Thank you for the presentation.