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

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.