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

@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.