atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems Chaining 66 blocks with AMP connectors

I have a bunch of 66 blocks with dual 50 pin female Amphenol connectors, where there's one on each side.

For a project I'm doing, it'd sure make my life easier if I had a few of these, but with 4 connectors (two on each side), where I assume the pair on each side is wired in parallel, where the two sides can be bused together with bridge clips.

Even 3 AMP connectors would work, if two of the three were wired in parallel. This would at least provide a way to chain blocks together easily, while leaving the third AMP connector available for "programming" with bridge clips.

A 66 block with 3 or more AMP connectors wired up seem to be rare beasts to acquire, but I know I've seen them before, both in the wild, and in scrap yards.

So two questions:

A) Is there a good source for these, or if recommending particular suppliers is bad, perhaps the proper search terminology for these. I've tried "66 block 4 amphenol connectors", and variations for the connectors, including "rj21", "telco", "50 pin", etc. There seems to be no standard way for distributors to name these connections.

B) Is there a clever way to "easily" use what I have (66 blocks with dual AMP connectors), but without having to punch a lot of wires between blocks. I'd prefer to use cables with the 50 pin connectors to "chain" the blocks together, instead of punching a lot of wires.

PS. If curious what this is for, it's for R&D and debugging a 1A2 circuit board I've been working on, a single board that can do most of what e.g. a 511A KSU can do; 2 RJ11 connectors in, 4 AMP connectors out. Features include an intercom and touchtone extension buzzing. Fun project, spent a few years on-and-off on it. Trying to wrap it up.

Greg:

By far, the most supportive manufacturers are either Siemon Company or Ortronics, Inc. I have to tell you that a pre-wired block with four connectors isn't going to be cheap. Here's a link to the page in Siemon's catalog that you're seeking in order to get part numbers.

SIEMON PREWIRED M4 SERIES BLOCKS

Ah, perfect.. much thanks, Ed!
With that I found a source that sells new ones for around $100, which which given the time it saves me to not punch it down, is probably worth it.

A vendor titled it a SIEMON 50PR BLOCK 66 BRIDGED, so I'm good.

And in fact, the 66 blocks I have are Siemon's too; they have the nice velcro straps to retain the connector.

You should be able to punch down 1 25 pair cable in 5 minutes , the time you spent searching took longer than that .

BTW, here's a preview of the 1a2 board I've been working on, the reason I needed the described 66 block.. a small electronics project gone out of control



Basically a "single board" KSU. Basically does what a 511a KSU does, but small, light, and with some added features.
Makes it "easy" to hook up a bunch of 1a2 phones for use with the usual features (Hold, call transfer, lamps, intercom, bells, buzzers, programmable ringing). Just add a 12v supply, some 1a2 phones, and some US style POTS compatible lines.

Still working on finishing touches, but it's pretty close to being done. Will probably make a webpage for it to "open source" the schematics, circuit description, board layout, manual.

Questions welcome.

> Basically does what a 511a KSU does
*551a*

That's a neat idea, I was wondering if anyone was doing something like this. All sorts of great features you could add without a wall board full of relays and boxes
Cool....

You can tell that it is a factory made circuit board. Very few people use 1a2 or 1a1 anymore except as an at home hobby . You can hardly find one used in a business . So what is the point? Please explain why I would one?

I have a pair of the yellow handle cutters you can see in the picture . I use the to trim my toe nails , they work really well for that .

In fact those yellow handles work so well trimming my toe nails I rarely have to use my burnishing tool to smooth them out .

look at three way amphenol bridging adapters. cpc or pcp.

Greg - that is too cool! Looking forward to seeing more of this project.

Jeff grow up it is all bullshit and wild imagination !

Thanks Jeff! I'll try to follow up with schematics and whatnot. Glad someone's interested.

Here's the circuit layout of rev B of the board. I included as much info as I could about the components on the silk screen mask so it could give someone a hint of what's going on sans schematics.



This is revision B of the board.. one thing that's wrong is the direction of the diodes for the "BELL CALL" section on the silk mask. When I got the boards back from the printer and soldered it up, phones wouldn't ring unless I desoldered the diodes and flipped them all around. Will fix that in rev C. Was surprised it mattered, I thought the bells would ring on either side of the AC cycle.. didn't catch that in R&D.

Schematics as they stand, 3 pages so far.

It needs a 12v/1.5A wall wart supply to properly run up to 4 phones.

Empirical tests with my VOM monitoring the 12v power consumption (+/-10mA) with 4 phones and 2 lines, it shows the card uses:

• 20mA when idle (no matter how many extensions)
• 800mA when in full use with Lines 1+2+5 off hook w/4 extensions
• Someone buzzing an extension adds 60mA

In the 800mA case, this means 12 lights in total are lit (3 per extension), 4 relays energized (2 per line), plus power consumed by the hybrid networks for intercom's and the active DTMF circuit.

It uses about +60mA when buzzing an extension.

It uses quite a bit more if a PowerDSINE is using the 12v to actively ring all 4 extensions; I couldn't measure it well because the 1Hz flashing line lamp was throwing off the reading, but the highest reading I saw seemed to add +500mA for ringing.

I don't have one of the Cambridge "black magic" ring gens to test, but I imagine they'd be similar in power consumption. I'll try to get a few for testing.

Of interest, during development, I used the AC ring generator from my old AT&T 551a, which I think puts out 30Hz (I never checked), but when my +12v PowerDSINE modules arrived, which put out 20Hz, gotta say, I prefer the powerDSINE's slower 20hz; a less strident ring. I should probably post a wav file comparing the two rings.

When I make a rev C of the board, I'll include a connector that makes it easier to attach the PowerDSINE ring gen, so that it can tap switched 12v from the board, so the ring gen is "off" when no ringing is present.

Anyway, on to the schematics...

* * *

Schematic - Page 1/3: Covers the relay logic used for the lamps, the A lead handling from the extensions, and the ring and line detect optocouplers, along with the hold logic path through the relays for the hold resistor. (A 160 ohm 1W resistor at the lower right). Small DPDT relays are used for the A lead handling (relay "A") and the line detect (relay "L").

Schematic - Page 2/3: Covers the oscillators for the lamp flash (2 Hz hold "wink") and ring flash (1 Hz during ringing), and the circuit that stretches out the ring detect to keep the ring lamp flashing in between the rings, and finally the ring lamp circuit that mixes the ring stretch and ring oscillator to flash the lamp.

Schematic - Page 3/3: Covers incoming call ring programming for bells, and I added a separate section that allows the buzzers be the audible for incoming calls, allowing one to hear calls without a ring generator. And finally, at the bottom, the DTMF detect circuit used to handle extension buzzing for the intercom.

* * *

Technical questions/feedback welcome.

Quite the job!


Sam

Here's a pic of the history of the project..

From top to bottom, the R&D prototyping boards which I started around the time I joined this forum, so exactly 10 years. Spent years on and off (mostly off) noodling the circuit and reading up on analog/phone circuit designs, studying patents, BSPs, product schematics. Then I started designing the board's circuit layout. At some point last year the project's inertia finally picked up to where I felt ready to print some boards, which became Rev A. Made some fixes, and a month later printed Rev B which I'm happy with:



I've done a bit of industrial circuits before, and this was no different, albeit more challenging. In particular, I found patent #4,093,830 the most inspiring; here's my version of it as a sketchbook drawing I made early on in the project:



It's a very simple line card circuit, and put me on the road to using a similar pair of optocouplers/pair of relays. I also liked the circuit description. It's clever use of transistors and the rarely used pin 6 on the optos impressed me too, but I didn't use that in my design, preferring my own techniques.

To layout the board, I used ExpressPCB's free software, which I highly recommend; very easy to learn and use. And their board printing service is quite good. Using that software locks you into using their service though; you can't take a file made with that software to other board printers. But this was fine with me; their printing service seemed fine, and I don't usually switch printers once I find one I like.

One of the problems I caught in the Rev A board: I took what I thought was a clever shortcut, using negative logic to run the lamps. This involved controlling the lamps via the ground wires, and tying the lamp signals common. This seemed OK because in the 2565 phone I used for R&D, the pairs of lamp wires were isolated. But turns out that /didn't/ work for the 2564 phones, which buss the lamp ground inside the phone. So fixing that involved switching to positive logic; NPN transistors became PNP.. which changed the gate logic a bit, causing more components. So Rev B works for all the 1A2 phones I had handy; 2564,2565, and 2830. Changed a few other things too, including powering the DTMF circuit only when the intercom is in use.

I'm pretty happy with the "Rev B", but will probably do a "Rev C" just to add a feature for the PowerDSINE ring generator, so it can be added in such a way that it's only powered when there's ringing, and completely off when the system is idle, so idle power consumption is low.

My goal with this project was to use old chips that were available in the 80's. No one-board computers or software. I could have easily used a PIC chip, Arduino, or RaspberryPi to do a lot of the timing and oscillators.. but I wanted to learn more about analog electronics, so working within that design goal allowed me to immerse myself in analog a bit more than usual. Consulted with an EE friend from time to time for general guidance.

I standardized on LM339 ICs as the main component for the logic and oscillators; these are "comparitors", a flexible gate-like device that are like opamps, but tailored to this type of analog work. I used power transistors that are overrated; they don't get hot or even warm during full use. Wanted to avoid having too many relays. I used relays where it made sense, such as redirecting tip/ring paths and ring voltages. Originally I'd used solid state for ringing, but decided against it for cost and flexibility.

My goal of avoiding computers was so that one could just assemble this board and it would work; no USB programming or software. Just wire it up and go. All the "programming" is in the circuit traces, and choice of components.

Another design goal was to have the board be easy to setup phones without 66 blocks, and use for the most common use; up to two lines, up to 4 phones, with programmable ringing and intercom with simple TouchTone intercom signaling. Basically all the features one would want out of a 1a2 system for a typical small office with front office receptionist and other employees. Intercom was important I felt as a default. Basically tried to get as close to a ComKey setup, but using 1A2 phones.

Will try to follow up with a short video showing 4 phones and 2 active lines, demoing ringing + buzzing + lights. 1A2 is so simple, there's not much to show really.. but it's nice to see it all working.

Greg:

Some random thoughts:

I'm not sure why that other fellow felt the need to curse out Jeff for being enthusiastic about your project. That said, I am intrigued by it. I don't find any part that's bovine excrement.

Have you, by any chance, taken a look at the "KSU-less" version of 1A2 that is used in the ComKey 416 system?
There is a 5th line add-on box that contains the electronics to provide "one more" CO line to a system that already is using its maximum of 4 lines. I have a spare if you'd like to hold one in person and see what makes it go.

You are correct in your discovery that 20Hz sounds much nicer than 30Hz. Thirty is used in subscriber key equipment power units because it's easier (cheaper) to derive than the "better" 20 Hz, used in PBX's and CO's. Cord board buzzers in models 550, 551 and 555, especially, sound so much better when powered by 20Hz. It produces a nice purr.

The Black Magic® 20Hz supplies are powered by a 5-volt input. I may have seen some whose inputs were (ISTR) 12, 24 and/or 48 Vdc.

It's too bad that you're not closer to Lancaster, PA, where, in June of every year, a hundred or so telephone collectors, and especially, "switchers" gather to display and play with their home-brew PBX and key system equipment. We are all members of C*NET. Check out www.CKTS.info.

I'd be delighted to speak to you privately about your project and a few of mine.

PSTN : 631-sevin for nyne-0100

C*NET: 1+ sevin for nyne-0100

EXchange numbers obscured to repel 'bots.

Jeff was not cursed out . It was my opinion he could take it or leave it . You should not Mother him he is a grown man and seems like a good person .

I think this is just fantastic Greg.
I was actually curious why you didn't have any processors or Raspberry Pi involvement or the like. It was interesting to read your design model above.
As I have thought about this type of thing over the years I had thought how cool it would be to have a phone module to plug each phone into that could communicate over wifi or ethernet to a central KSU or possibly Asterisk appliance so one wouldn't have to run 25 pair wire everywhere.

I actually built a 2 line phone system that was similar in function to 1a2 from scratch in the early 80s when I was in jr high school. I still have it somewhere, Ill have to post pics of it. You guys would laugh your asses off but it worked for my dads office!

@Silversam: Thanks!

@RotaryDialTommy:
This project is indeed not something a sane person would do,
it was more a learning experience and something I'd wanted to do for a while.
Cost wise, it's probably not cheaper than a 551a on ebay, but it is lighter, lol

@DimensionSeven:
Your wifi idea sounds neat. I'd actually thought about using
1a2 over wifi, but I wasn't familiar with digital to analog for voice
when it came to converting two wire to four wire. So I held back
on that project, as it took me too far into D/A, A/D telephony.
I might try that as a follow up project, though!

Of interest for 1A2, there are cell phone bridges that can connect
cell phones to POTS, and therefore 1A2. I looked into that a few
weeks ago, the box is around $100. Was curious to experiment with that.
The reviews on Amazon for the product were mixed, but promising.

One 1a2 feature I regret I didn't want to get into is an auto attendant
and voice mail, two features that have been important for my business.
Having an auto attendant feature gets rid of robocalls! I have an AT&T
1080 system with that feature, and love it just for squashing the 4 or 5
junk calls per day my business lines get.

@Arthur:
Regarding ComKey 416: yes! Some ComKey 416 features
inspired me for this project, esp DSS and intercom.

One of my folks worked at an office where they had a 416 system,
and I was familiar with its operation by talking to the head
secretary; she knew all the features, and showed me on her
primary set, which I remember was a great deal larger than the other sets.
So I was familiar with how it worked.

Later they ripped out the 416 system (early 80's), switching to
a "horizon" system, IIRC. (I recall it had a different ring, and
maybe fancier buttons?) Again, the same secretary showed me the new
system. She had noticed my interest in the phones, and thought
to rescue a 416 satellite set from being tossed out, which I still have.
Has a rotary dial. So as a young teen I studied that quite a bit.
I have a drawing I made of it on my ComKey 416 page:


Great modular design internally. Never had or found repair schematics
for ComKey phones, though, so there's a lot I don't know about their
internals. I also never got around to opening my primary set, hrm. Don't know
if I should be scared to look or not.

Some years ago I purchased a touchtone satellite 416 set, pic of it here.
..and later, bought a primary set off ebay. That was great, because
then I could actually get it all working as intended.

At the time access to ComKey documentation even on the net was limited,
but was able to find some hookup docs, and reduced it to a single document
I also posted on my ComKey 416 page.

Re: C*NET, nice; thanks for the link, and the offer to discuss stuff.
Indeed I don't find myself on the east coast much anymore; used to
live there. Not missin the cold!

When you stated "Never had or found repair schematics for ComKey phones, though..." are you talking about BSP 518-450-105?
It is available if need be HERE, unless of course you are talking about something else

Nice job, although I can't see any commercial market beyond collectors and hobbyists.

What amazes me is that you are able to have a "one of" board made for prototype purposes at reasonable cost? Back in the stone age when I was doing stuff like that I had to draft my layout by hand on mylar with stick-on tapes and pre-made pads for the components. Original was 3:1 which was photo reduced to a 1:1 negative. That was used to mask a copper clad PC board that had a photo sensitive coating over the copper. After exposure to UV light you wash the board in a solvent that removes the coating where it wasn't exposed to the light. Then you placed the board in an etching solution that ate away the unprotected copper leaving the traces. After that you cut and drilled the board then you were ready to stuff it.

There was PC board design software available but it was very expensive and as you can imagine slow on the 286 machines we had back then. We've come a long way.

-Hal

@Prof Shadow:
Wow, thanks! Yes, I've grabbed quite a few of the cowboy's PDFs, but missed that one. That's a /much/ better version of what I have, which is BSP 518-450-106 in a crappy paper xerox form. The documents are similar, but indeed the PDF has schematics I /don't/ have.. weird!
I looked thru your PDF; it has some nice info, but it's missing all the IC's and quite a bit of the logic stuff, and circuit description. What the BSP's call "schematics" I'd more call a detailed wiring diagram; they cover the relays and transformers, but not the ICs, and details of transistor circuits. That stuff gets tricky. What I'm looking for would I guess be more of a "service manual", something the guys at WE/Bell Labs would have to troubleshoot and repair the circuit beyond field repairs. Those kind of documents cover part numbers, ICs and transistor logic. For instance, I've seen some of these for after market line cards. And I think on cowboy's pages, I found an actual WE schematic of a 400D card. A full diagram including the transistors. No circuit description though. IIRC, it was a bunch of GIFs I had to paste together to get the big picture.

@hbiss:
Yes, not many markets for sure, lol.. I'm not looking for one really. Just wanted to make a professional solution to this, to see where it would take me. Bones up my circuit board skills, and I actually find it fun. One market, though very slim, would be for film/tv and theater prop rentals. I work in the film industry, and have made technical solutions for many years, though mainly in special effects. Often I see 1A2 "not done right", not only in period pieces, but even in film/tv shows of the 60's/70's/80's. The most common thing is no lights, or lights not operating correctly.

Regarding "one off" boards, most pc board print houses offer small print runs for prototypes. In my case, 2 boards for 2 layers costs around $350 to print, 4 days or so to arrive at my door. That includes silkscreen (white text) and solder masks (green coating to cover the traces to prevent shorts from stray solder). It's cheaper to do a run without the silk and solder masks.. I think about half that price? I have few other hobbies that involve cost, and no significant other to tell me to "curb my spending habits", "get your power tools off the dining room table", or "stop using the living room as a workshop" : D

I remember the "masking tape" days of early circuit design. Ugh. Had to do that back in the mid 80's -- didn't like it one bit. I actually wrote some simple CAD software (in DOS) in the late 80's to layout circuit boards and pads. Single side only, but it spit out PostScript that went to a laser printer that was sufficient for the board printers to use instead of tape up. They'd make 1:1 prints of the page onto clear acetate (kodaliths?), one for drilling, one for traces and pads. They'd include those acetates along with the boards on delivery. I recall the cost for a few one sided boards with various holes was around $180 in those days, including their printing costs for kodaliths. I think I still have the invoices somewhere. Since they "stack" the boards before drilling, one board isn't much different than two.

I do have a friend that makes his own single side boards at home from time to time, when the board is simple enough. He has jars of chemicals and whatnot; a brownish green murky liquid that eats away the copper. I've never done it. That technique is best for surface mount boards; no or little drilling. Tricky for through-hole stuff like mine though; tough to drill tiny holes accurately without a computer controlled drill press, and some of these connectors won't go in at all if you're just a little off. Single side boards also suffer in that, without through holes, the solder pads "peel off" easily. With double sided boards, there's actually a cylinder of metal connecting through each hole, which increases pad stability.

Following up on the 400d "functional schematics" that omit details vs. a full schematic; here's the 400d from one of the BSP's that is commonly found:



Now in comparison, here's a more detailed schematic; note part values and transistor arrangement details:



The transistor arrangement is important for someone studying tricks and techniques, as well as detailed part troubleshooting for dead boards. I tried to reverse engineer a 400D once, so as to make a page on how it all worked in detail, but it was too hard; reverse engineering makes me crazy unless I were to de-solder everything.. didn't want to go there. Figured I'd wait until documents turned up.. and they did!

If you know of a source for the actual WE service manuals for e.g. line cards and ComKey, I'd sure be happy to know about 'em..! I assumed they were few and far between because they probably never left the repair labs. Circuit descriptions are even more useful, as one can learn analog tricks/techniques. That patent I mentioned a few posts ago has a great circuit description, I learned quite a bit from that alone.

I had the Service Manual, Vol 2 years ago. Is that what you are look for?

Here it is: Service Manual

The Bell System, being, essentially, the only game in town, and having their own vertically integrated company, did not need to print or distribute details that could fall into the public's hands. There were no component-level field repairs expected, therefore no field repair documents.

Some engineering documents can be found, in excruciating detail, in the BSTJ, and the BTR. (Bell System Technical Journal and Bell Telephone Record.)

After that, there are SD's (Schematic Drawings...you displayed one above) CD's (Circuit Descriptions) and of course the lowest form of documentation, meant for the repair force's field reference, the BSP's.

As time went by and the repairman's job was dumbed down, the schematics in BSP's were also simplified, as you have seen, when looking at what you know to be a complicated circuit, but shows just a few block diagrams where "a miracle occurs" as the old cartoon stated.

Those of us who worked in the golden age of 1A2 and EM PBX's jealously saved and hoarded the original, detailed, BSP's and would refer to them when the "new & improved" versions didn't offer the detailed help that was needed.


[img]https://i.imgur.com/EXmmL.jpg?fb[/img]

@Prof Shadow:
Thanks! While I do have Vols II and III of the BSP's (again, as bad xeroxes.. a pile of binders about 5" thick), and recently located Vol I on cowboy's BSP site (wish I'd had that 10 yrs ago!), this is again a much nicer version than I have.. and having text-searchable PDF versions is waaay better. Also, wow, there's /color/ in some of these documents? (pp.53 of that pdf -- red arrows showing the path to ground for lightning). I should probably toss my ugly xeroxes in the recycle bin, along with the silverfish that are munching on it, and just depend on the PDFs at this point.

While it does say it's a "service" manual, as Arthur points out, there's limits on how far the BSPs go into detail. The BSP's seem to be "field service", as opposed to.. hmm, what's the term, "engineering" servicing, where e.g. dead line cards or burned out ComKey mother boards would go for servicing, to determine if they're salvageable or blown beyond repair.

@Arthur:
Thanks -- the "Bell System Technical Journal" seems like a very good lead -- that's a big rabbit hole to go down, great! Excruciating detail indeed; some of that stuff is like reading Scientific American; heavy on the math and physics of electronics and telecom.

Apparently IEEE and Nokia have teamed up to make these available as PDFs.. looks like that's a "join and pay" situation to access the articles, at least from what I gather on the IEEE page. Seems there's other providers as well. Would be interesting if they have articles focused on business phone systems and key system design/architecture. I'll sniff through the abstracts.

But I also found what I think is a "free" a way into the documents via archive.org; there's a page a bit easier to browse there, titled The Bell System Technical Journal (1922-1983); an "infinite scroll" of thumbnails of the first page of each article.

IIRC, there was a guy from England (?) here on the forum some years back who was interested in studying 1A2 design, and sounded like an EE guy who wanted to go down a similar path to the one I've been taking. I think that thread might be locked, but he might be interested in those BSTJ articles as well.

And finally, a demo video for the "1 board KSU".

When I wrap this all up into a single webpage (along with some other stuff) I'll post the link here.

Thanks. I love the video, however my wife wasn't as impressed...sheesh!

Very nice, small footprint.

A fun project, I guess?

Sam

@Prof Shadow:
Yes, there's no fame or fortune in 1a2.. no one I know is very impressed at seeing these old phones work. People who get this bug are few and far between.

But it's a damn good and solid design IMHO, worth supporting just to keep the old hardware accessible to modern folks.

There seems to be quite a few people who like these phones and want to try to get them working somehow. There are hacks to make land lines work with 1a2, but they don't get the lights and features.

That was another goal with making this board -- to make the phones work as they're supposed to, but with a minimum of setup.. an ease of use that's tough with the old shoe boxes. They worked great in phone closets and mounted on backboards, but aren't great for simple demos or quick and easy setups where people want to dabble with the phone sets themselves, to pull them out once in a while and noodle with them. Having to dig out my big ol' KSU prevented me from doing some fun quick demos for visitors interested in this stuff. This board would make such a demo quite a bit easier. I'd have to mount it in a case or something, I guess.

Greg,
The video is great. Thanks for sharing that.
On the intercom I thought I would mention a somewhat odd thing I have on my system which is a Tone Commander FL2000 flashing light adapter. It was discussed in this thread: https://sundance-communications.com/forum/ubbthreads.php/topics/571611/2
Long story short it works with the station intercom to flash the intercom line light at ring cadence on the called station only. All other stations show a steady "in use" line light.
As all the guys pointed out in my original thread it was a lot of extra hassle and expense (and individual line 5 light wires) to make it work and was definitely a fancy "nice to have" feature and uncommon. But I thought it was kinda neato and unusual but it was a pain in the rear to implement in my system.
However after seeing your topology it seems you could probably implement it fairly easily. That is if you were super bored and wanted a totally useless but interesting feature.
Here is what it looks like in operation:
Shawn

This cat approves!

Viking Electronics made a "Micro Key" 1A2 around 1984 or so. 3 RJ-11's for the dial tone, Amphenols for the phones. Remove the ringer from the phone, remove the buzzer from the phone. Mount a 100-ohm speaker inside the housing, or use a spare U1 handset receiver element wired across the yellow/slate pair and another across the yellow/orange. Remove the locking key from the 4th pickup button. An audio generator spit out an obnoxious tone over the Y/S pair's speaker for ringing. Com on the 5th pickup button, go off hook and use the 4th pickup as a momentary button to open all of the other speakers on Y/O pair to make an all call announcement for someone to pickup the com line or a holding line. The only one I put in for my family's camera shop ran for 10+ years until putting in a Partner.

Wow, Tommy! I don't think I ever ran into one of those. Matter of fact, I'm sure. I would have remembered the business with the speakers. Very clever.

Sam

@TTTommy, that's a great idea, replacing the buzzer + ringer with a speaker.
The ComKey systems basically did this; built in speaker did ringing, buzzing, DSS/paging and speakerphone IIRC.

An an elegant solution to creating a built in paging system. And I imagine removing the heavy ringers made the phones a bit lighter. And with tech available even in the 80s, one could have 'played' actual sound samples of ringing or buzzing to the speaker, much like modern cell ring tones. (Though in those days, everyone seemed to "like" the modern digital beeps and weird game sounds..though most were really annoying..!) Here's a ComKey ring for reference (turn your speakers down! Not sure if I recorded this from my own 416's, or if I found it on the net)

I tried a quick google search for "viking electronics micro key" but couldn't find any relevant hits. I also checked Viking's page to see if they had a special section for old discontinued product manuals, but didn't find much. Do you have any pics of the device, or maybe an old manual? Sounds great. I'd thought about modifying the phones to make the whole ringing and buzzing thing easier, but at some point I decided not to make a hybrid system, but instead drive the phones exactly as they are.

@Dimension7:
Flashing lamp on the buzzed intercom extension is a cool feature!

It's kinda practical too, for instance I could see if two extensions are near each other, but far from the caller, it might be hard to tell which extension was buzzed -- "Was that your buzzer or mine?"

Yes, this board could do that with some simple modifications.

For the lamp bit, it'd just be a matter of having separate transistors for each extension's Line 5 lamp, instead of just having them all commoned together from one transistor as I do now. (Currently when the intercom is picked up by anyone, the lamps all come on and stay on until hangup, regardless of who's being buzzed) So that'd be 4 power xstrs instead of one. They're cheap, a buck or two a piece, so no biggie there, and the xstrs don't take a lot of space. Some extra traces on the board cost nothing but space.

Where it gets a little tricky (space + cost wise) would be having a separate ring timer circuit (what I call "ring stretch" on my board) to keep the one lamp flashing for some amount of time after each buzz (probably about 10 secs) That'd be another LM339 IC, socket, and hand full of passive components to pull that off. But there /is/ a signal from the MT8870 (dtmf decoder chip) that stays set after the button has been released, which I could use to "remember" which extension was last buzzed to keep the correct lamp flashing. That'd avoid needing flip flops for "memory".

Neat feature, not sure if I wanna add that one or not, but it might be fun to figure out the logic.. simple logic gets tricky when you actually have to incorporate it effectively, while keeping the component list down. (This is why software makes this sort of thing sooo much easier)

Yeah, it is a bit of a odd feature but you are right the software aspect of it makes it a lot easier. I wont post a pic of my backboard (because its a mess) but in order for it to work on my system I have a Melco intercom and its 66 block then the FL2000 and its block plus all the associated wiring.
The FL2000 is just a transistor board with a couple of relays. When the intercom line is activated off hook all line lights go on. Dialing an intercom extension then triggers the FL2000 (connected to the station buzzer lead from the intercom) to start the interrupter and then flashes the called extension. If you leave the calling extension off hook the called extension will continue to blink forever presumably. If you stay off hook and dial another intercom extension the FL2000 will change and blink the new extension. Hanging up the calling extension cancels the interrupter and drops all the line lights.

Neat but COMPLETELY superfluous in general
Shawn

I cannot count how many times I have been on a customer site fir the first time trying to reprogram a defaulted database and the customers have no idea who's telephone ring on incoming calls!

Shawn, it's okay to post it, but perhaps under a different thread.

Greg, I'd be very interested in purchasing one of those boards.

I'm interested too, I have been wanting a smaller alternative to my 551. Also do these dazy chain so you can have 4 lines and an intercom? or are you planing to make an expansion board.

Just an update regarding the 1a2 board project; I've made a website for it now:
https://seriss.com/people/erco/1a2-multiline-board/

It' has a few more details, including a circuit description. I'll be adding to this page as time allows.

Currently I've only documented the REV B board, which works fine, but I want to add a few features for the PowerDSine ring generator module, so that it doesn't receive power until ringing is needed.

I found the PowerDSine modules run a little warm even when idle, so to keep power use down while the system is idle, I plan in REV C to provide a couple of extra terminals to supply switched 12V/GND to power the PowerDSine only during the presence of ringing.

I'm also in the process of seeing if I can convert the board over to some different software so that the boards can be printed by other, more cost effective board printing companies, as the software I'm using now, great as it is, is locked in to a particular printing company, which does a great job, but is a bit expensive for small board runs. Doing this conversion may take some time, and therefore REV C may take a while to print up. I have it laid out already, but find the cost a bit prohibitive to make another run using that company.

Nice job!

Imagine of you used your powers for good, instead of evil!

Just kidding!

Seriously, great work.

Sam

Weekend project that, even through got out of hand, turn out amazing!

Dead link: https://seriss.com/people/erco/1a2-multiline-board/551a-ksu.html

@ProfShadow: Ah, thanks for the dead link notice.. I'll need to make a page for my 551a, as I don't already have one. For now I put a stand-in page so it doesn't 404 at least.

BTW, I've updated the webpage to include a better circuit description, and I also added the board's .pcb file (used to layout the board and have it printed). See the page for details if you're interested in that.

Relevant to the subject of this thread, I used that same software to make a small pair of boards that converts 1A2 50 pin rj-21 into (3) rj-45 cables and back at the other end, so one doesn't need a full 25 pair cable to do long runs between the KSU and phones, and without punch blocks. With one RJ-45 cable between the boards, one can get Line 1 (TRLA) + ringing. With two cables that adds L2/L3 (TRLA), and with 3 cables adds L5 and buzzer (e.g. intercom). One can leave out the middle wire if one just wants L1 and Intercom with ring+buzz. There's two boards needed, one at either end of the RJ-45 cables, with proper male vs. female rj-21's for each pair. Here's the "phone end" of that board:

The "KSU end" looks similar, but with a different sexed connector, and thus the trace layout is a bit different. I'll probably make a separate page for this little pair of boards at some point.

This is super cool.

It's really awesome how we can just make this stuff these days.

Greg, where did you source your 8p8c jacks? I'm working on a project and having one of those on the board would be super helpful. I got a link from someone in another thread to some, but I want to see what else there is. Also, is the pin/hole layout pretty standard with those? The PCB design program I use has some preloaded in there, but before I commit to making a board I want to make sure they are going to work.

Now that is cool!!

Great idea, but please don't get me started on the "RJ21" and "RJ45" subject! What you're doing is something we used to do back in the day, especially in residential 1A2 installations. It was amazing what we could accomplish with a six-pair pre-wire loop. People don't ever think about feeding from both ends!

@ChrisRR: The 8 pin RJ-45 jacks were sourced from Digikey (am I allowed to say that?), pretty sure. Anything else I'd have gotten from Mouser.

BTW, I'm working on a new rev of the board which should be cheaper to construct and easier to assemble (less parts/soldering). *So* many folks have been asking to purchase these boards, I figure I should try to see if I can at least make a version that I could build and sell in small quantities of 10 or 20. I just can't see myself doing the original board in that quantity; too many tiny parts.. it takes me almost a full day to solder all that and test.

So on this new board would use a single 20 pin one-chip computer (PIC chip), replacing 5 chips, 2 relays, and about 50 resistors/capacitors.

I also want to rearrange all those square transistors (which run the buzzers and lamps) so they can be screwed down, which should make the board more durable for shipping. Arranging the components that way uses up more board space, just about the same space I gain from decreasing the chip count.. so the board ends up being about the same size (a little smaller), but more durable.

Unfortunately using a one-chip computer gets me away from one of my original goals to use discrete parts that are 100% replaceable by just purchasing and replacing, e.g. due to lighting strike. The PIC chip must be purchased and then burned with the firmware to make it work. The device that uploads firmware over a USB cable is about $50. But with that, one can program any number of PIC chips, and even change/edit the software.

Anyway, I'll follow up here and on the youtube page if I make any progress on that.

I don't think too many people would be opposed to using a PIC chip. As long as the supporting circuitry is designed correctly, there's no reason to think it shouldn't last a long, long time. That being said, it would also be cool if the programming of the chip was available for download, or at least keep a pile of them around pre-burned so if someone's does go belly up, getting it going again isn't impossible. (Might be worth making the chip socketed)

There are some PCB houses that will make up the whole board for you and it's generally pretty cost effective. Beats soldering oodles of these things together in your spare time. Conversely, you could just sell it as a kit with a board and a bag of parts for those of us that can solder on our own. My guess is, you'd find a pretty ready market for the DIY approach.

I'd take a day to solder one of those up. What a great way to get some of my display phones operable without much hassle or a fat wad of 25pr running back to the phone closet. I could screw that to the back of the cabinet and just plug the phones in directly. Then its just a couple pairs to hitch up to the pbx.

Coming out of lurk mode to say that this is one of the coolest threads ever.

Greg, your all-discrete version of the board is a true thing of beauty. I understand the desire to create a PLC version and completely salute that effort, but if the bare boards were available for the current version, I'll bet folks would buy them as well.

Just the bare board and a parts list... Give people the fun of tracking down all the parts and putting it together themselves. A great learning experience that would keep me off the street for a lot longer than a day! [Us olde pharts are a lot slower with stuff like this...]

Jim
==================================================
Speaking from a secure undisclosed location.

Another update; so I've moved forward on the PIC chip version of this board to bring the parts count down, and can probably make this available to people as pre-assembled boards, as there's many folks who seem to want one of these. NOT YET, as I'm still in development, and not even quite ready for alpha testing yet.

So a temporary progress page on this new PIC chip version of the board is here:
http://seriss.com/people/erco/tmp/pic/

It looks much like the 'all discrete' version, but with many less resistors/caps, and no LM339's.
The board is also a little smaller, and cheaper to print now that I got away from the other software I'd been using.
With this new software, I can have the boards printed for about 1/3 the cost, or less! And with the extra room freed up
by the lower parts count, was able to mount the large transistors flat to the board so they don't flop around. (Metal fatigue
of the transistor pins was a concern when mounted vertically, so this is much more structurally sound)

I went through a 'round of printing these new PIC boards, and just today finished writing the software firmware
for the PIC chip that handles all the logic of those LM339/analog circuits did.

I'll update the above page with that firmware code later today, for anyone interested in PIC chip software.
The PIC chip model I'm using here (there's many, many models by the way), the one I'm using here is a PIC16F1709,
a 20 pin chip that has the exact number of I/O signals I need for this project (which is 17).

I also bought an XLink, a cool little ~$60 box that acts as a bluetooth gateway between a cell phone and a land line.
It was an easy one-button setup, and an easy way to get your old phones to ring and make calls over a cell phone.
I could see multiple cell phones appearing as separate lines on a 1A2 system, for instance. Worked fine for me;
it gives a fake dial tone when you pickup, and uses the touchtones to make the call. I'm not sure how it knows when
you're done dialing to initiate the call, but it does work for the normal US numbers I've dialed. (1+areacode+7 diigts).

I made sure the new board can work with that device, as it's probably typical of IP phones as well; the ring
voltages are slightly different (lower voltage) than most CO's, just enough to ring a regular model 2500.
So I adjusted my ring detect circuit to make sure it properly detects ringing for that lower voltage too.

Anyway, at some poin, when I'm ready for testing, it'd be great if I could send a test board to one of the mods
of this BBS (who lives in the continental US) to try out for testing/feedback purposes. I know it's only
about $25 to send these boards through the US post using one of their standard priority mail boxes.
So I could send you one to try out, and then you can mail it back to me when done testing.

👍🏻

Beautiful work!

Quick update: got the new PIC version of the boards back from the PCB printing service (REV E), and quickly soldered one up,
loaded the PIC firmware, and it works! Tested with a couple of 1A2 phones (2564's). Here's a pic:



I could probably build 10 or so of these, perhaps at the rate of one per week. Kills half a day soldering it up and testing.

Anyway, for those interested in this board, I'll try to make them available somehow.

But would love first to have one of the tech guys who admin sundance-comm to test one out, just to see if there's anything I should
know about or add. If there's any takers, let thyself be known, and I'll contact you via PM/email and send you one no charge.
All I ask is you foot the approx $25 USPS bill for shipping it back to me after a few weeks/months of testing.

PM sent.

PM sent



Sam

OK, I have two takers, ChrisRR and SilverSam..
That should be enough for beta testing, thanks!

ChrisRR confirmed receipt of his board and got it working.. SilverSam's is in the mail due to arrive Wednesday. Pics of their two completed boards, just before sending:

Looks like you took the Mechanical out of Electro-Mechanical.

This thing amuses me to no end. I love messing around with it. I'm going to take it to the TCI show in Lancaster, PA and show it off.

@Prof Shadow:
Don't worry: those little yellow/orange rectangles are mechanical relays, so there is some clicky-clicky action during use: one clicks once per ring, the other clicks going into/out of hold.

@ChrisRR:
Sounds great -- have fun at the show with the board!
My advice: just keep any metal from falling on it or possibly getting under it, or it'll be a short demo, lol.

If you decide to mount it to a board (feel free to), either use standoffs or use a trick I sometimes use when I don't have those handy; cut the rubber insulation off a round 3 conductor power cord/extension cord, trim into 1/2" little cylinders of rubber, and use those as standoffs.. works great. Compresses a little when you tighten the screws down, but stiffens up into a sturdy structure.

I wish I knew somebody with a 3D printer, I'd have them make a nice case for it.

I'd thought about this too, though I'd thought about finding a metal chassis about the right size.

I'll bet there's some pre-made presentation cases that would work fine for this if you wanted to get fancy.

I once had an old backgammon case that looked something like this:

..and that did come to mind

Hmm, I haven't actually tried this, but since the board is 12VDC, you could probably power your demo with a single 12V lantern battery (or two 6v lantern batts in series). That'd get you lamps, buzzers, intercom.. might even handle powering the 12V ring generator (a PowerDsine) as well for bells and everything. A portable PBX, lol.

Or maybe you can re-purpose some of those 12V rechargeable lithium batts many screw guns use, which probably have more amp hours, and is easy to recharge. I actually have a 12V screw gun with a pair of batts.. I guess I should try a test to see how long I can run a couple of phones this way.. will follow up if I can.

ChrisRR: OK, that screwgun 12v battery test with the board worked out pretty well, actually.
Shot a couple of quick videos below showing the test results.

Turns out the one Ryobi battery can manage all 4 phones for bells, buzzers, intercom, the works, with no wall AC needed. The little PowerDsine ring gen rang all 4 phone's bells pretty well, even though I think it's a 3 REN device (?).

Video #1: 4 x 1a2 phones + KSU powered by a Ryobi screwgun's 12V batt battery.

Video #2: Volt meter showing the battery's output voltage running 4 x 1a2 phones

Some extra details:

• The battery's output voltage did sag a few 10ths of a volt at the end of each bells/buzz/intercom test, so I'm not sure how long one can sustain this type of use on a single battery charge before the lamps get dim and the DTMF dialing and CPU power stops working. For instance, in the 2nd video, the meter starts out showing 11.76v when the KSU is idle, and after a run of tests and return to idle, the batt is down to 11.72v.
• The single batt used in this video had already run several tests before I made the video, and it started with a full charge showing about 11.82 or so.
• The two batts for my Ryobi are about 3 years old, and gets a lot of use, so they're by no means new batts. But I do always keep the spare on the charger.

I ran a 551C with one of those 12v to 120V inverters, once. I had one of those cell phone to pots adapters for a CO line. A truly mobile 1A2 setup.

The fact that your board runs natively on 12 volts makes all kinds of things possible. I know one of the TCI guys had a 1A2 system set up in his motorhome.
It would make it really easy to have it battery backed so it would still work in power outages.

HMMMM.....
The mind wanders...

I figure a $120 APC or Tripp-Lite battery backup UPS (Uninterruptible Power Supply) could keep a 551x working through a power cut, though not sure how well the UPS would like the large surge from initial power up/down of the large linear power supply transformer in the 551. I use a UPS to protect my business phone system and A/V equipment from random power cuts.

For some reason the local power substation likes to explode from time to time, once it sent a surge so large it blew up 3 devices; my business phone system's power supply (an AT&T 1080), a DVD player, and something else I can't remember. I opened the DVD player and found the power protection varistor had blown completely, and left a large black spot on the board and on the metal chassis. Replaced the varistor to fix the player, and had to replace the phone system wall wart.

BTW, I did locate my old backgammon case which I'd used for various industrial purposes over the years. The board fits inside perfectly.. here's an actual pic (instead of the obvious photoshop mockup I'd posted earlier in this thread):



I guess I could mount it to a board that fits inside, so I don't have to drill through the case.

I like that. That's snazzy!

Very cool!!

I should probably start a new thread for this board thing, but thought I'd follow up I'm working on a board revision that can handle rotary too. A few people have asked for this; some on the web, and one request from ChrisRR.

Detecting rotary is a trivial circuit (a single optocoupler, the same as the ones I use for ring and line detect), and with a PIC chip it should be pretty easy to count the pulses, and from that determine which extension to buzz. I imagine I should buzz for about a second. (With DTMF it buzzes for as long as the touch-tone button is held down, but that doesn't work with rotary, so I figure I'll need to set a fixed buzzing time)

That board is slated to be Revision "F", if I end up making it.

Still in R&D on that one, but had good luck analyzing a very clean, almost like new 565HKM phone (that smells like hair spray for some reason) I just acquired off Ebay to work with. The rotary seems to generate pulses that are around 65 msecs long, with 20 msecs spacing, or around 11.7 IPS, if I measured correctly.

Is the spec for adjusting the rotary mechanism documented in the BSPs somewhere? I found a wikipedia page that went into this detail saying, more or less, phones in the US were adjusted to be between 9.5 and 10.5 IPS, which is a little slower than my phone. Perhaps unadjusted phones "wear out" and go faster? Or maybe those numbers are old, and newer phones were adjusted to go faster.

The page also went on to say switching equipment could handle a range of between 8 and 12 IPS, and that operator rotary dials could go as fast as 20 IPS.

I need to know all this to implement into the firmware, so that it can tell the difference between dialing and other non-dial generated "noise".

If anyone can add clarity to this, let me know. I'll dig around in the BSPs for the 565HKM, but I'm not sure the documents I have cover this subject, especially on the exchange end of things. I guess docs for the strowger switches might cover max/min dialing speeds, as I take it until electronics came along, those were the devices that were direct-driven by the rotary impulses, so the pulses had to be slow enough to drive the solenoid mechanisms in those strowger switches.

I mostly asked because I have a pile of old rotary keysets in beautiful condition, and with VoIP and everything else changing the rules about how phone lines are supposed to work, they are getting harder and harder to use. Sure, I could put them behind my Partner system since that has a pulse to tone converter built in, but where's the fun in that? I have managed to discover that the Grandstream HT series ATA's will support rotary dialing. They are fricken finicky though. They really want 10 PPS(IPS) do or die. Some of my rotary phones work with them, some don't. Someday when I have patience I'll make a jig to connect my phones to my O-scope to measure them and adjust them... To be completely fair, probably 90% of my wired phone usage is the Partner 18D sitting on my desk. My main contacts and a pizza joint are all programmed to the buttons, along with the contact closure that I wired to the garage door openers. People come to the house and text "HERE" (which I friggen hate) and I just smash the button to open the door and let them in.

Some may call it lazy....

I call it efficient.

Chris, thanks for the rotary info.

I found it's not that important to know the exact specs for the rotary, as it turns out it's kinda easy for the cpu to tally counts from the rotary no matter how far off the timing is; as long as it's in a very broad ballpark. So I came up with some firmware code such that even hand clicking gives entirely reliable results. And I've been using a noise reduction algorithm with debounce and hysteresis that takes care of switching noise really well.

So with that R&D out of the way, I need to just finish up the "board bridging" feature, which lets one join two boards together so that 4 CO lines / 8 Extensions can be supported easily. Just adding a 40 pin ribbon cable to bridge the two boards, and changing some jumpers (still working on that last part) to get the line assignments to all line up across the two boards. This way all 5 lines on all 8 extensions can be active; lines 1-4 for CO, and line 5 for intercom. Lots of blinky lights!

So all that would be in "REV F".

Oh, and here's a pic of that nice 565 HKM rotary phone I acquired for testing. Great condition, and a nice smooth dial. The cord makes my whole office smell like hairspray though.. hoping that fully outgases over time, lol.



It's quite a beauty; it's been kept in perfect shape all these years. Many thanks to the ebay seller for such a nice phone.

That's really nice!