Hacker News Reader

You can see them in action at Avoncroft Museum of Historic Buildings[0] which includes a working telephone exchange.

About a mile from there is Droitwich Transmitting Station, an ArtDeco era station, see page 13 of [1] for exposed knife switches with 400V.

[0] https://avoncroft.org.uk/avoncrofts-work/special-collections...

[1] http://www.bbceng.info/Operations/transmitter_ops/Reminiscen...

There's a functional mechanical switching relay, the kind triggered off of the clicks of a rotary dialing wheel, attached to two phones at the communication museum in Frankfurt https://www.mfk-frankfurt.de/ and you can dial one phone from the other, and see the relays move as you enter the numbers.

My dad worked at the phone company and as a kid in the late 1970s I went into the switching room with him on a Saturday morning (he was the district boss and would bring donuts in for the folks that had to work weekends). Forty years later and I still remember lots and lots of clicking and a heady smell of ozone.

Worked at a telecom API provider and we were told AT&T still has a handful of these in service in the US.

https://www.youtube.com/watch?v=xZePwin92cI