A walk through the 5XB [annotated] 

I was going to say the same thing. My dad worked for Western Electric and ended up with AT&T after they dissolved Ma Bell.

That's a good idea! Interestingly, the PCB you see in this video is not even custom. It was designed by CMC Corp as a replacement for the relay-based pulse counters that used to occupy that space. Sometime in the 1980s, New York Tel (where these senders came from) decided to replace their aging revertive pulse circuits with these solid state versions. I'm not sure if it was because they could no longer get official replacement parts from Western Electric, or they just grew tired of testing and adjusting the old relays. (We also have the original parts that used to occupy that space stored away in a frame nearby, but they are just sitting there, unused.)

I had the same question, wondering if this switch was in active production use. Seems like a lot of activity if it is just for museum display. Makes more sense that it is all being driven by simulation scripts.

It's a python program that I wrote. The amount of traffic and the calling rules are configurable. It has several front ends, (console, physical buttons, web app, API), and it speaks to the switches using Asterisk + DAHDI and a T1 interface. The calls are not simulated--they are real calls. It's just that the originator of the calls is a computer and not a human. github.com/connectionsmuseum/panel_gen

That's the ALL or Auxiliary Line Link. It could be "bolted on" to an existing line link frame to widen it, adding more lines to fill out a set of junctors that was underutilized.

Didn't you work in NORVA?

This is 13 lines placing “random” calls. The timer is also randomly chosen, but ranges between 12 and 20 seconds per line per call.

@@ConnectionsMuseum yay synthetic loads

Yep!

It’s a replacement for the RP pulse counting relays. Replaces 0-9, 0’-9’ F0, B0, OF, and STP. Made by CMC. Don’t know anything more about it. These out senders came from NYC I think so we don’t have any historical documentation for them. We do have the original relays on mounting plates too, so we could put them back, but this board works very well.

It’s a replacement for the RP pulse counting relays. Replaces 0-9, 0’-9’ F0, B0, OF, and STP. Made by CMC. Don’t know anything more about it. These out senders came from NYC, so we don’t have any historical documentation for them. We have the original relays on mounting plates too, but they’re not currently in use.

@@ConnectionsMuseum Thanks. They just looked out of place.

@@ConnectionsMuseum Neat. Thanks.

@@ConnectionsMuseum I think stuff like that is very interesting, it shows just how long the service life of these switches was, and what was done to extend it further. A couple of the connectors on my step switch have solid state relays, and all of them have a current regulator installed, they keep the loop current at a constant 23ma regardless of loop length. The regulators were custom designed for a particular CO, I have the schematics and they have the name of the town in the title block. I just think it is really neat that these switches entered service in the electromechanical age, and didn’t leave it until well into the microcomputer age in many cases.