Post #2318546
2026-04-30 07:40 UTC
@lpbkdotnet@mstdn.social They’re called U points because the shelf contacts for jack-in selectors and relay sets are U shaped, as just about discernible in this photo.
I don’t think that your ringer contacts are the same as U points though, are they?
Replies (1)
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@lpbkdotnet@mstdn.social 2026-04-30 08:08
@snaprails@cupoftea.social I'm not convinced by that, because the term is way older than jack-in selectors The most convincing explanation I've head was that it's related to the shape of the diagram symbol - and early diagrams I have do look more like ___U___ than the more modern ___V___ However even that doesn't come from any source I'd treat as authoritative! I think the original derivation is probably lost to time! A bit like those false etymologies for 81s being "A.T.1s" etc