Wow, thats suprisingly easy to read!

Hoe gaat het met jou ?

helal olsun.. harikasın

Thank you for your genuous sharing

Sounds glorious… greetings from England.

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!

I have been trying to find a crossbar switch (or a few) to purchase. Do you have any suggestions? Kind regards.

How did the system work before the invention of an Arduino? How was the number dialled remembered before being sent to the selector?

Thank you for this explanation - I've been trying to understand how crossbar exchanges worked for a while now. You made everything very clear!

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.

Hi the 75 Volts ring is rms o peak to peak? thanks

Can I buy such a telegraph from you?thank u

Can I buy such a five needle telegraph from you？thank you

No Way. I have been fighting my esp32 for hours to trying to show up on my iphone BIG THUMBS UP

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.

i am useing same library for esp32 but it showing name in NRF app in IOS but not showing in IOS Bluetooth setting place help me.

Nice work Wim, Is there a way to do this all with only arduino or esp?

Thank you for this in-depth explanation of the Wheatstone Cook Telegraph!

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 😂

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.

How many connections can this switch handle? Seems to depend on where the two respective lines are on the switch.

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.

Thank you so much for this video sir

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. kzfaq.info/get/bejne/f5Okiqh-qJuVe2Q.html

Beautiful!

thanks a lot

beautiful ..i lived a bit that age ,before all went digital

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.👍

Een prachtig YT kanaal heb je Wim, misschien vind je de mijne ook wel leuk :-)

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.

Wonderful explanation, it makes me feel young again remembering the sound of the crossbar switch, thank you

How many simultaneous calls can this device switch?

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 ...

Very cool 😊😊

Is it possible to call from number 4 to number 3?

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

I designed a crossbar relay set for Telstra back in the day when it was telecom Australia.

cool.. 👍

interesting thank you!!

Thank you for this most interesting and informative video; fascinating (though I had to watch it more than once to take in all the information!)

What a great invention! Very easy to use by anyone! Thanks So Much!!!

How much is it worth

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. 🙂

thank u!

I don’t think I grab anything whatsoever in this tutorial even tho it appears it make sense!!!!