sundance-communications.com/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems Can you guess what this is?

I'm working on a little project to bring back a 1A2 gizmo that seems to be made of unobtanium these days. I have some custom made PCB's on their way to me, but they haven't come off the boat from China yet. Here's one I threw together on a piece of perf board. It is the exact same layout as the custom PCB I designed and almost a perfect copy of the original. Can anyone guess what it is and what it does?



I hastily pinned it to my backboard and hitched it up, and it works just as well as the original. I will be making 50 of these to start, and if anyone is interested in them, let me know. (obviously once everyone knows what it is)

Is this a solid state interrupter? I've heard that 118 ring generators are made of unobtainium these days, but it is way too many interface pairs for a ring generator here.

MCT66 is a dual channel optocoupler, so can be a lamp extender (but then I don't see any high power MOSFET to drive the lamps) or a line ringing detector. Anyway I ran out of my guesses.

Very good catch on the dual opto. The two opto's are paralleled. If I ran down what the conductors do, I'd probably give it away. Suffice it to say, it runs on B battery, the two transistors take one of those conductors to ground, and last hint, there's two pairs of series diodes (1N4005) across two of the conductors, each pair in parallel, but in opposite directions.

Anyone?

OK another hint. The leads are (in descending order) GND, A, RING OUT, RING IN, TIP OUT, TIP IN, B-Bat.

Rats...I was going to guess T, R, A, A1 LG, L, B1, R1

There's only 7 wires going in, Dean.

Note the lack of A1......

I botched the wht/brn lead and just extended it by soldering a little jumper.

Quick reminder, this isn't some contraption I dreamed up, it's a clone of a once common as dirt piece of 1A2 apparatus.

Well I'm older than dirt and I can't place it. Manual intercom's the only thing I can come up with, but no talk batt.

My first thought was a 400 card but not enough parts:

36-400-201 ITT 400E