atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems Can you guess what this is?

That page you linked had a link to the US version of their site. It's tough to design a board around parts you don't have, and it's hard to order parts if you don't know whether the program has their profile pre-included. I still have 30 or so of version 1 to solder up and get ready anyway.

Let me pose some questions to anyone who would be interested in these things.

What would be your choice for making terminations to one of these? A pigtail, an 8p8c jack, screw terminals (most expensive option), or other suggestions?

Would anyone be interested in a model that had four loop detectors in one package? The parts are simple and cheap enough, getting the board designed is simple enough, problem again is what would be a preference for connections?
For the four way model I was kind of thinking 6p2c jacks for the incoming and outgoing lines and then I'd only need 6 connections for battery and A leads.

I'm open to thoughts.

I haven't heard from RedBul for a while. He might be interested...unless he all ready has miniaturized 'em.

All this talk about A lead control wiped away some cobwebs in the old brain. In the 1987 AT&T Premises Distribution Products Catalog, two A lead adapters were listed. The Z153CM adapter provided A lead control for a single line phone where there had formerly been a key telephone set. Like the regular 153 adapters, it consisted of a female amphenol with a modular jack for a single line phone, but there was a small circuit board in the hood. I recall that these were sold hanging up in blister packages in the AT&T Telephone Stores in the late 80’s and early 90’s.
The 354A adapter was similar except listed to provide A lead control for a two line phone or two single line phones used in conjunction with a 267C adapter.
Have not been able to find any additional information on these adapters on EBay or the internet other than the AT&T practice number for the Z153CM (461-099-006PS).

I would want to see a Phoenix connector, popular these days. Surely you have that layout. But your choice of connectors depends on where that thing is going to be installed so maybe RJ jacks in and out with Phoenix for power? Also, you have a lot of unused real estate on that board, you could probably cut the board size down to 1/4 what you have there. If you are going to do one with multiple controls you're going to have to shrink the layout down anyway otherwise you'll have a board the size of Kansas.

-Hal

Hal, I kind of just went with the layout of the original Melco for that. I figured it was a good place to start. If I really put my brain to it, I could probably fit four on a board not much bigger than the one I have now. I’m trying to stay away from surface mount components because I don’t really have the means to solder them efficiently. Heck, if I went SMD, I could fit 6 on a board the size of the original. Through hole soldering is much more friendly for the home gamer. I was thinking I could fit four on a board about 4x6” pretty easily.

Absolutely agree about SMD. Maybe if it was around 30 years ago when I had better dexterity and could see without a magnifier I might think differently. But for what you are doing that's fine. I don't know what the Melco looked like, I never saw one. The ones I used were housed in something like a 1x2x3" plastic box. RJ-11 on one end for the SL device line cord and a line cord on the other with a RJ-14 plug on it for the T,R and A lead control. There may have been a cord to a wall wart but I' thinking it was line powered.


I did quite a few fax machines but they actually had A lead control on pins 2&5. Matter of fact I'll bet that you can find fax machines today that still have it. The times I needed A lead control was usually for answering machines. Single line phones I would modify for A lead.

-Hal

The problem with the line powered devices is they won't retrieve a call off hold. Most of the loop current is going through the hold bridge in the line card and there just isn't enough to work a relay coil. It's fine for getting a lamp so no one grabs the line or stopping the ringing when a call is answered, but they just will not cancel the hold. The melco devices, and by extension, my devices, will. They (in theory) will work on as little of 1 ma of loop current. It's actually looking for the 1.2 volt drop across a pair of diodes in series. That 1.2 volts lights the led in the opto and that fires the two transistors that pull the A lead to ground. It's devilishly simple. And for us nutcase collectors, really darned handy. If I answer a call on my 1A2 set on my kitchen counter, and then need to run into my workshop, I can grab the call on the partner phone out there no problem. When I was using a line powered loop current relay, I couldn't do that. It wouldn't fire when a call was on hold and I'd just hear hold music instead of the caller. Someone was asking me about creating a setup similar to mine with a 1A2 in conjunction with a Merlin system in his case. I figured it should be pretty easy to replicate the Melco, since the sandman relay I had just wasn't cutting it. That's what started this whole misadventure.

Now I'm going to have to look and see if my fax even has pins 2 and 5, let alone be wired for a leads....

Melco's

Wow pretty cool project.

Hello All!

My name is Ron, I live in Hilo, HI (the Big Island - where the volcano erupted a few months ago!) and I am running a 551C - with a mix of 8 phones - 3 lines and intercom.

Ten plus years ago - this forum - Ed and Arthur in particular - gave me the advise, wisdom, equipment and encouragement to set this all up here - and it has worked flawlessly in all of those 10 plus years!

I currently am running 3 MELCO S64-1's on each of the 3 lines - for FAX - Satellite TV - hand held etc.

I now need to add a 4th line - and of course I can find red hot lava 20 miles from my front door much easier than another MELCO S64-1!

I do however have a brand new Viking LDB-2 on hand (Ed must have sent me this - I sure don't remember it!) but while I understand the T&R in and out and all - what leads (and how) do I wire to the LDB-2 for contact points 5 & 6??

Any advice is greatly appreciated! (And Chris - I'd consider buying 4 of your new boards if you are so inclined?!?!? - Please advise as well!)

Mahalo and Aloha!

Ron