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by ssl-3 82 days ago
> The main catch is that they have a 50-pin Centronics style connector on them which you will have to break out somehow to your RJ11s.

This is just another lost art (traditional phones are either dead or are instead IP) that I once learned a fair bit about:

The name varies regionally (I've heard them called Centronics, cinch, and CHAMP; though around here, we call them Amphenols). The Easy Method is the same regardless of name: It centers around a split (aka "50 pair") 66 punch block[1] that is mounted to a wall, or to a wall-like object.

Buy a pre-terminated 25-pair cable with the right connector on at least one end, and punch that down in order[2] on one side of the 66 block. That connects the system to the punch block. Importantly, those wires never get touched again.

Phones (or more precisely, wires for jacks for phones) connect to the other side of the 66 block. Those wires also never get touched again.

The two things (phones, systems) are connected/disconnected with bridge clips that combine the two halves of the block (which only allows 1:1 ordering, but that's often just fine).

Alternatively, a "we fancy!" variation uses single-pair cross-connect wire so that arbitrary phones can quickly be connected to arbitrary system ports -- maybe on completely separate blocks.

After that, plug in the Amphenol. Plug in the phones. Have fun talking to yourself.

(Or, at least: That's an easy way for small stuff. Bigger stuff (hundreds or thousands of pairs) eventually really wants better organization, but punch blocks are still normally the order of the day there, too.)

[1]: https://en.wikipedia.org/wiki/66_block

[2]: https://news.ycombinator.com/item?id=41428998

1 comments

Instead of 66 blocks and punch down tools how about something like this: https://www.showmecables.com/icc-telco-male-patch-panel-rj11...

I know we ripped out similar, a plastic panel/wall mount version, at an old job when we went VoIP. The Centronics came out of the PBX. Probably find on eBay or surplus. Maybe talk to IT and they have one hanging around in a junk pile.

> The name varies regionally

Micro Ribbon connector https://en.wikipedia.org/wiki/Micro_ribbon_connector

Sure. One end of the 25-pair cable can be cut down on a patch panel. There doesn't need to be a 66 block.

Or a person can buy a patch panel pre-assembled with an Amphenol connector, and just plug in a 25-pair cable between that and their gear. Here's one from Leviton: https://leviton.com/products/49012-j24

Or, there's unholy creations like this octopus breakout cable, which can be used to connect existing patch panels/structured cable plants into Amphenol world: https://www.sandman.com/products/cbl3c-6-foot-qwik-25x2-cabl...

And those kinds of things are great for rapid deployment, but we're not trying to do that -- are we? We're just goofing around with old telco stuff for the lulz.

The most tinkering-friendly option is 66 block (wherein: the structure is whatever we want it to be today), I think. Punch down tools are cheap (including those that have interchangeable blades for also doing tidy work of 110 keystone jacks). It only takes a few minutes to land all 25 pairs, and those pairs can do anything a person wants them to do.

Meanwhile, 66 blocks themselves: They're dandy things. I've used them in the field to build simple circuits: The resistor or the capacitor doesn't care that it is hanging off of a punch down block instead of soldered to a PCB. It works, and it's wall-mountable for permanence.

But yeah, there's certainly options. I've got good familiarity with 66 blocks and their ability to quickly (and rather universally) hack stuff together, so that's what I tend towards using.

> Micro Ribbon connector https://en.wikipedia.org/wiki/Micro_ribbon_connector

It's always important to know the specific and most-correct nomenclature, but it's equally important to use terms that others easily understand. :)

Like, the 4-pin Molex connectors in common use for things like PC optical drives (where those still exist). You probably know exactly what I'm referring to, and can picture one in your head whenever someone mentions a "Molex connector" in the context of a PC.

But those aren't from Molex -- they're instead from Amphenol's Mate-n-Lok line. Molex sells compatible-enough versions (as do countless other manufactures), but Molex had nothing to do with the design or introduction of that part.

Meanwhile: The square 4/6/8/20/24-pin jobbies that connect to things like video cards and motherboards, and that seemingly everyone calls ATX connectors? Those actually are Molex parts (from their Mini-Fit Jr line), but people would be confused AF if you called them Molex connectors.

So if we're doing it right in casual discourse, we use the terms that people understand -- even if they're not necessarily maximally-correct.

I've never witnessed the term "micro ribbon connector" used in face-to-face dealings involving telco stuff.

---

Up next: The male 1/4" audio connector. Is it a headphone plug? A guitar plug? TR? TRS? A phone plug? A jack plug? "Like an aux cable but bigger?" Yes, any of those terms work. The best term depends on the audience.

The connector originates in the forgotten world of plug-and-socket telephone switchboards, so of all of those options "phone plug" probably gets the history most-correct (and that's also what Radio Shack labeled them as). But that specific terminology is pretty archaic at this point.

It's so archaic that if I asked a sane and rational person for a cable with "phone plug" on it these days, they might go looking for something with 6P4C, 8P8C, USB C, or (maybe!) a TRS -- depending on their age and/or upbringing.

I've worked in industrial automation and with computers for a long time and have come across a LOT of connectors. It helps to know the exact nomenclature when specking parts or finding replacements. My recent search was for Russian RP10-11's on Vacma motorized vacuum valves (the look like big D-sub connectors.) Not an easy search and luckily found a guy on eBay.