Love ur channel when I was a child I bully a simple telephones with two single stage stepper switches from an old jukebox the logic relays wires by hand bully a line-finder out of like 10 relay witch were coned with two or three supervisory relays could only do one call at a time had the line-finer cross connected to control ringing to cutoff ringing when answered used ringing supply from 1A 2 system used 24 volts for talk 24 Volts for main logic 12 and 18 volts for the test it was a little bit of a mess but it worked. Had used interrupter also from 1A2 System. System had no dial tone or any tones at all guess I could add that in lol 😊🤓🙂🤗🤗🤗🤗🤗🤗🤗🤗😬🙄😎🧔🏻🤓 The system still works today! Love what you did here so much!! 💕❣️💜🌈
It’s very interesting. I grew up in a section of the city that was run by a crossbar #2 exchange. What if you had 5 phones wanting to call on that switch. How could a call to extension 18 happen if extension 17 was already engaged in a call? That part doesn’t make sense to me. Wouldn’t that disrupt the call on 17? Thanks for this demo.
Amazing! I visited the radio museum in Gothenburg last week, and one of these was mounted on the wall. I took a photo, but couldn't imagine what it was. Using the museum's internal catalog number (RM06446), I found it in their database and then your great video demonstrating how it works. Bravo!
Hey, i seem to have a problem when uploading the code and i wonder if someone could help me. First of all thank you and great Video! Onto my problem: I am trying to use this code to connect my phone to my esp32 to control a dc motorboat some of my friends an me have been building for a school project, but the issue that I am facing happens when I try to upload the sketch onto my ESP32 WROOM. I get this error message: "Arduino: 1.8.19 (Windows 10), Board: "ESP32-WROOM-DA Module, Default 4MB with spiffs (1.2MB APP/1.5MB SPIFFS), 240MHz (WiFi/BT), QIO, 80MHz, 4MB (32Mb), 921600, Core 1, Core 1, None, Disabled" D:ESP32_UART\ESP32_UART.ino: In member function 'virtual void MyCallbacks::onWrite(BLECharacteristic*)': ESP32_UART:65:52: error: conversion from 'String' to non-scalar type 'std::string' {aka 'std::__cxx11::basic_string<char>'} requested 65 | std::string rxValue = pCharacteristic->getValue(); | ~~~~~~~~~~~~~~~~~~~~~~~~~^~ exit status 1 conversion from 'String' to non-scalar type 'std::string' {aka 'std::__cxx11::basic_string<char>'} requested " I've tried to search after similar error messages but did not get any smarter out of that. Did I forget to install some library or additional content? To run this I have just installed the Arduino IDE Version 1.8.19 and the ESP32 Dev Module Board. Any Help would be greatly appreciated Have a great day!
Hi Jeffery, Crossbar switches are apparently difficult to find. I got mine from the Houweling museum in Rotterdam. It was the only spare. Maybe they were more widespread in Sweden? I don’t have contacts there but there should be an Ericsson legacy society.
Mark, The dialled number was stored in a number of uniselector-type mechanisms. These uniselectors were then stepped back to their home position whilst at the same time stepping the 500-point selector. This process required a fair number of relays. The register was only required during the setting up of a call and could be shared by a large number of selectors. Detailed description can be found in the Ericsson Review journal and Telephony II by J. Atkinson.
@@wimderkinderen1952 Many Thanks - Do you know I haven't seen my copies of Telephony for about 45 years, they are probably in the wardrobe upstairs so far back they are in Narnia. This mechanism strikes me as being very high precision and therefore may be a little temperamental unless cared for by a highly qualified professional engineer, so not ideal for your normal Butt-Phone wielding GPO gorilla.
Thanks, a real blast from the past. I spent 30 years looking after this equipment in the Uk mainly in and around Derby. I have fond memories of those days. Many hours spent cleaning banks and changing wipers and magnets. My Farther also worked as an installation engineer installing and upgrading these exchanges.
Wonderful project!! I managed product and installed LM Ericsson PABX's in the USA for over10 years i the 1970's. ARD-561, AKD-741, and French Ericsson CP-100. I probably installed over 100 systems. I love crossbar systems. Would like to get a crossbar switch myself and build a project like yours.
Yes, Martien, an Arduino or ESP32 in combination with some additional components (Songle relays or MOSFETs, and a ringer module) could do everything, but …. bringing the vintage stuff to life is more fun 😂
@@wimderkinderen1952 Thank you for your answer. I like this technology. Unfortunately I don't have the room en money to use Crossbar switches or step by step switches. Yes it wil be more fun in the original style😉
I fitted these as PABX for Serk Services in Redditch. Marvelous piece of kit worked 100% out of the box, far superior to Strowger. Fairley weird operator's console. This worked for a good 20 years with minimal maintenance.
I'm old enough to remember what a pain in the butt crossbar relays were to adjust. While doing it, I used to think back fondly to step-by-step (Strouger) switches 😂
It took me quite a while to get my head around the operation of a crossbar switch. It is inherently more complicated than Strowger. But the story goes that they required less maintenance?
@wimderkinderen1952 crossbar switches took up a lot less space per extension and used a lot less power. Cleaner, faster, and quieter, too. But they would go out of adjustment (contacts and wires) at the drop of a hat - or minor change in temperature and humidity; airconditioning was a LOT more important with crossbar.
I have tried to sum up the demo in the text below, please review and correct any errors in the description, this would help me understand. The crossbar switch as shown is a latched finger mechanical memory reserving (holding relay) pairs of phones or conversations for a maximum of 4 simultaneous conversations out of 18 extensions (2x9) with one pair (19,20) reserved for line finding and control (Tones and ringing). This would increase the equipment density in the routine of calls by about 10 to 1 as compared to a Strowger click and bang. The microcontroller is used as a basic counting decoder and tone controller, which controls the crossbar to route calls between two extensions (numbers) that it decodes (it knows how many numbers are needed to dial, and includes a timeout after a lengthy delay if the number dialed is incomplete). This is different from the Strowger which integrates simultaneously counting, routing and memory (which is ensured by its basic operating technique). In the USA, traditionally for land lines, you have an area code (three digits, know as long distance), followed by an exchange code (three digits) followed by the number within the exchange of up to 10,000 numbers (0000 to 9999) with some number sequences reserved either by starting digit or number depending on the function. So, in basic terms the challenge before us is to create separate telephone exchanges of 10,000 numbers each, such that the equipment used must be able to detect, count, route and remember (while the call is in progress) with a maximum of 5000 simultaneous conversations local to the exchange, although I link only a small percentage is really used like perhaps 10% for a maximum number of simultaneous conversations of 500? Although, this number probably expandable if the billing statistics result in too many blocked calls.
My specimen can have four connections and therefore can handle two calls simultaneously. Each call engages two holding magnets. The connections are multipled between contact banks, so each connection can be routed through any of the four vertical relay blocks.
That's a great description of how crossbar works. Previous to this, it was all just "black magic" to me... now it's all quite clear. I didn't realise crossbar switches were ever so small... but I suppose it's obvious they would be - for private switchboards.... that's perfect for tinkering with - very "hobbyist friendly"... I would love to have one. I thought we only had "ring, ring....... ring, ring...... ring, ring......." in the UK.... I thought the whole of the rest of the world was "Briiiiiiiiing.......... Briiiiiiiiing.......... Briiiiiiiing" like in North America. In my projects, I always call it "the UK ringing cadence".... I'll have to find out how widespread it actually is, and update my documentation.
I loved this, it was very nostalgic, and while I didn't get into telephony until the early 80's when the company I worked for was using reed switch crosspoint switches in their larger exchanges and SCR crosspoint switches in their PABX's. I also loved your almost totally non-computer based (torch and camera) presentation method.
Very good demo. Love it. I also did a presentation demo at some point. This is just to illustrate how the machine works. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-I-tWEMC51K0.html
De crossbar en hefkiezers zijn mij bekend, maar wat mooi om ze in jouw demo setups te zien. Dit is inderdaad de mooiste techniek die er bestaat. Zelf heb ik dit spul helaas nooit kunnen bemachtigen, dus deze video’s maken het weer goed. Een prachtig YT kanaal dit.👍
Vielen Dank !! Ich war kurz vor dem Aufgeben als ich auf Dein Video gestossen bin und jetzt doch noch etwas funktionierendes in Sachen Bluethooth auf ESP32, iphone und der App gefunden habe, wo ich jetzt einen Startpunkt für meine Anwendung habe.
Each call requires two holding magnets to remain activated. My crossbar element can have 16 extensions but only two simultaneous calls. That is why a telephone exchange has many crossbar elements.
0:24 yes i know they were used in exchanges................. I HAVE ONE IN MY BEDROOM haha and yes it is as cool as it sounds and yes, it's as bloody heavy as it sounds Talk about Heavy Matel... Pick up a crossbar switch sometime....... Just 1 Now.. that's an Ab Workout EDIT 0:45 OK, I SEE I HAVE A FORMIDABLE OPPONENT and we are going to compare scars like they did in jaws LOL My one was ..... Ever so graciously donated to me by the 2 gentleman at the Decommissioned Telstra Exchange in Melbourne , which is now known as the Telstra Exchange Museum it's not open to civilians, it is however open to techs and me and a friend some years back while doing our Open Cablers Registration were told quietly by our instructor that by appointment we could visit the exchange Museum I cannot stress how cool it was Not only did we see multimeters that had NIXIE TUBES.......Ohhhh that was electronics porn and a half Not only did we see Underground Telecomms cable so thick it would make you feel indimated Not only did i see the old Mickey Mouse and Garfield Phones of the 80s Not only did i get to use an old hand cranked Phone to generate the AC for the ring I GOT TO USE THE ACTUAL PATCH PANEL, THAT THE GIRLS USED TO USE IN THE PATCHING DAYS. I successfully made a call from the panel to a phone, step by step via old Telecomm's procedure and we got to see "The Rack" we got to see the underground decommissioned tunnels where i was convinced they kept the bodies of deceased Lines men that were being preserved and genetically modified to form a new super race of Telco Lines man LOL But yeah, when these guys gave me the crossbar switch... I'm lying if i say i wasn't emotional. IT WAS SUCH A NICE GESTURE, Forever Grateful
Love the old electronics ... many good ideas for modern bits hidden away back in the days of people actually thinking. Thanks. Great video. Look forward to checking out your channel. Subscribed. Cheers ...
Yes, as indicated in the schematic, extensions can be multipled between contact banks. So, if 4 calls 3, the extension of 3 in the second bank will be used because 4 already locks holding magnet V0.
Hi Wim, good work! It's not easy to explain how a crossbar works since the insides are mostly hidden. I like your demo using a "paper clip" to assist in closing the relays contacts much like how the selecting finger works in a real XB switch. Your demo is clean and looks great! - Al
Thanks for your comment. I had a quick look at your excellent videos and will have another go later. Is this your equipment or do you record the videos in a museum? Best wishes, Wim
It took me quite a while to understand the crossbar switch. It is not as straight-forward as the Stronger selector. I hope that the introductory section with the separate relay helps to grasp the fundamentals of the crossbar switch.
Thank you for this video, I was originally a Strowger BT Technical Officer in South Yorkshire UK. left BT as an Ericsson AXE10 engineer and became a consultant (1998) at Ericsson Stockholm Network Operations Centre. I came across the bank system as part of demonstration at the Museum of Engineering in Stockholm whilst working and living there. Fascinating how both Strowger and this system had group and final selectors but used differing mechanisms as you have indicated the design of these systems was admirable. 🙂
