There’s an old adage about waiting hours for a bus only for two to appear at once, and for Hackaday this month we’re pleased to have seen this in a run of analogue telephone projects. Latest among them is the video below the break from [Wim de Kinderen], who is demonstrating the workings of a mechanical crossbar switch with the help of a vintage Ericsson unit and an Arduino replacing the original’s bank of control relays.
It’s possible everyone has a hazy idea of a crossbar array, but it was fascinating from this video to learn that the relays are worked by metal fingers being inserted by the bars into relays with wider than normal gaps between electromagnet and armature. This extra metal provides a path for the magnetic flux to actuate the relay.
The machine itself then is an extremely simple and elegant electromechanical device with many fewer moving parts than its Strowger rotary equivalents, but surprisingly we seem to see less of it than its American competitor. The video below the break is definitely worth a watch, even if you don’t own any analogue phones.
We recently saw a similar exchange implemented electronically.
First few pages of a text book on it.. I think I know someone who has the whole book. Just sayin’
https://www.telephonecollectors.info/index.php/browse/bc-switching-library/western-electric/weco-switching-documents/weco-crossbar/no-5-crossbar-book/1029-00-contents/file
Bob you tease.
Oh my, oh my… Please, please! Put the whole chapter!!!!!
Oh come on, the whole book is on the same page:
https://www.telephonecollectors.info/index.php/browse/bc-switching-library/western-electric/weco-switching-documents/weco-crossbar/no-5-crossbar-book/
“The video below the break is definitely worth a watch, even if you don’t own any analogue phones.”
ATAs make that dream possible.
Can you reccommend any (cheap, one- or two-line) ATA’s that understand pulse dialing and allow currents to support old-style ringers?
Grandstream seems to be the vendor of choice for pulse
Grandstream HT-801. Just got a used one for $9 on eBay and it works great for pulse dialing and even ringing my old Western Electric rotary phone.
Thx, unfortunately I can’t find used ones on the Dutch 2nd hand sites, a used one from US + shipping + import fees is more than a new one here, which is a bit steep but I’ll keep it in concideration. Thx!
Sort of related, exploding the phone is a great book:
https://explodingthephone.com/
Thanks for the link!
More than sort of related: The Connections Museum in Seattle
https://www.telcomhistory.org/connections-museum-seattle/
See and touch an actual working switch: SXS, Panel, Crossbar, ESS
The Telephone Museum in Ellsworth, Maine, USA has two crossbar switches (Western Electric #3 and #5) that were originally in service for New England Telephone up to the 1980s. Both are functional and you can place calls through them with the phones installed around our campus, or over C*Net. Stop by during the summer for a tour. We’d love to have you visit.
https://thetelephonemuseum.org
So cool! I go up to Maine every summer, had no idea this was there. Definitely will be making a stop! Thanks for the self-promotion.