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

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.