Please never stop making these. You are incredibly awesome

I'm Sarah and I say we need to use the whole thing :) Best attitude for a museum, run it all and demonstrate it ALL! That panel switch is an amazing machine, they were so lucky to have been able to save it!

There is so much architecture that was designed in such a thoughtful and solid manner. It is mind blowing to think this was all achieved mechanically with motors, electromagnets, and wires. In many ways it reminds me of how computers work, only you can see this machine in action. You can’t really see what a computer is doing. That’s what is so jaw dropping about it. It was invented so long shop by some very brilliant people. The Leonardo DaVinci of telephone switches people. Not many people could have figured this out. They were special people.

For some odd reason I'd really love to work on this gear. That loom wiring is impressive along with Sarah's knowledge. I wouldn't want to be touching it without her help!

Cool video Sarah, thanks! I worked for Bell Canada...we changed X-Bar and a Step Office to Nortel DMS-100 in one exchange in the city of Windsor, over the course of three weeks and every week I went down to check progress, it got quieter and quieter until the total cutover... I just heard cooling fans and no switches. Very eerie...and it was the end of an era. Thanks to a museum like yours, we won't forget. Sad, as these switches were pretty reliable for how they were made. Real workhorses!

Very cool that there is someone around that still understands some of the older technology of communications. Thank you so much for showing this. Really interesting. I wish I knew you personally. I'd love to see this first hand.

What amazes me is how much the panel office is an electrical analog to what operators would have done in a manual office.

This is so interesting, I'm so glad of having found this channel. I knew nothing about how telephone networks worked, old or new, and now I'm glued to those videos.

This is crazy technology, thanks for sharing all this stuff with us!

Seriously some of the coolest stuff on the internet. Awesome job!

You are awesome, Sarah. One day I hope to make it to this museum, it looks incredible.

I think you would make a good teacher. You put things in a way that can be understood. Excellent.

Really cool deep dive. Your knowledge and enthusiasm is so infectious

Great description. Basically this line finder is a processor built using binary logic and do-while-loops, processing input bits and pulses according to state machines, along with some timers, driving output bits and pulses. Quite fundamental yet when you stack everything up it is an extremely complex system.

I love watching people work on something they very obviously love. Superb :-)

Loving these videos. I don't travel much but to visit family; your museum is where I'd venture first.

Watching your videos.... Makes me happy :)

Great Video Sarah....... Well explained....Massively cool machine.

Wow. With this one video you have answered several questions I've never understood since I worked for Ma Bell back in the early 70's. Despite me being the webmaster for TCI, my own BellsyStemPractices.org/ website, and all the switchers I know, I've never gotten an understandable answer as to what exactly a line finder does. It finds the "subscribers line" when their phone goes off hook. I had always pictured it as something to do with locating a trunk line, which didn't make since considering where it is in the circuit. That's something that seems to be so obvious to those in the know, that it never occurs to them to explain that to the layman or museum visitor. I remember seeing those rotary step switches you explained in this video back when I worked in the old materials receiving dock in the Western Electric plant in Arlington VA. I could tell they weren't part of a SxS 'mail box' switch because they were too big. Now I know what they were used for. I could never understand how the vertical cross bar switches worked or what they did before now. I am continually amazed at the geniuses of Bell Labs and Western Electric. Most brilliant folks of their time. Sara is getting much better with her videos. Keep up the good work Sara. You're teaching an old phone nut new things.

You are so talented!! This is art!!

this seems so archaic compared to today digital switch. still love it from where we came from when phones still relayed on maniacal systems to connect calls

Can anybody explain how a telephony anomaly that i was part of (back in the late 1970s or early 1980s) could have happened? When I was much younger, our rural communities were served by the small, independent Red Hook Telephone Company in upstate Dutchess County, NY (sold first to Continental, then to Frontier, as best as I can recall). One evening, I picked up the phone to find many other people already in conversation. Apparently, anybody that went off hook was just joined together in one big "party line" scenario. This party was well under way before I joined and overall lasted at least several hours. Folks just dropped in and out just by picking up their receivers. (I have friends who still recall that day, so it wasn't just the fevered dream of a young telephone phreak.) I'd been in the CO a few years before and at that time they had an ancient frame type system - lots of moving parts. I'm not sure if that was still in place when this event occured. Any ideas how this could have happened and on what type of equipment?

Great video. I'm an old Panel switchman.

Amazing Stuff! please keep up the work on these amazing old things :-)

Nice Video. Good job. I'm a long time XB5 Switchman. All I know about a panel switch is they work by magic. However if you need help in wiring a XB5 marker route relay please contact me.

COOL HOW THSE WERE EGINNEERED MECHANICALLY BEFORE DIGITAL FRAMES

I like this human. Very entertaining!

Excellent, really good to see young guys picking up this knowledge, most of the people who worked on this stuff are well gone not to mention the gear.

Thank you Sarah. This line finder contraption is part of the step-by-step exchange is it? Great video. You’re excellent at explaining/teaching.

Interesting connections

What is a line switch and does your fact about first line finders include step switch line finders?

Awesome 😁

Love your videos Sarah, you are awesome!! Question: How does the line finder detect an off-hook condition? An off-hook condition applies a short between the tip and ring (48v and Gnd.) so the line finder has to detect this condition somehow. I installed ESS equipment for Western Electric. Ferrod sensors were scanned to detect off-hook in the line switch frame, but this thing obviously had its own thing. Thanks

ya know what I haven't ever seen anywhere... is an explanation of the circuit of how the line finder even knows there's an active line to find.

I can’t wrap my mind around how much physical space a phone call used to take. Are the subscribers wire hooked up to more than one line finder poll? So if one was in use a different poll would activate? Or would everyone wired to the same poll just need to wait for someone else to finish their call?

Sooo...unless I missed it (very possible) each subscriber is wired across each column in its bank to potentially engage each vertical LF. My mind is still blown how calls are handled in the CO to subscribers in the same CO. How is each subscriber line split when it enters the CO into outbound and inbound routing? It seems there's so much extra copper to handle that and the redundancy that there must be some esoteric DC capacitance and impedance issues.

I'm curious, what happens if you go off hook and there are no selectors on the linefinder available? (We were served out of a step office when I was growing up, and that never seemed like it was an issue in stepworld...)

2:56 I would like to know why there's a twin-lens reflex camera mounted sideways to the panel, just to the right of the dial and below the ammeter. It is pointing to the right and doesn't look as if it could photograph anything, since most TLRs wouldn't focus closer than 1 meter.

What is this an old central office that never got took apart?

That LF hasn't worked since I was born? Holy cow!

So what were the constraints on these - like does that mean the total number of subscribers who could make phone calls at once is the quantity of rods that exist in the selector? That seems like a really tiny number of rods to select calls for 300 subscribers?

Sarah, IT DIDN'T WORRRK! :D

what tells the line finder which line to find?

It looks like you read my mind. The whole thing should be working and you guys should simulate mothersday or something lol

The point of a line finder is economy of scale, but you wonder how much economy of scale they are really getting by adding all these flip-overs and special logic and ... Are they all controlled in common? So there's only one logic circuit that selects one line at a time, using whichever rod is available but only one at a time until that one is done and then finding the next call with a different rod?

Moar panel videos please Sarah! :-)

Where is this place and why?

"I'm not smart..." Oh, stop it, ya are too! You're smarter than me about this stuff!"

Huh... I was expecting counter weights instead of springs. I guess that was a space/weight issue.

"...In a new office...." Well... in a new _panel_ office, that is.

Need to hire a retired Apparatusman to clean the cork rolls.

UwU?