Bell 1A2 KTUs
Posted 24 August 2012 - 10:58 AM
Posted 24 August 2012 - 05:54 PM
I've played around with a few key systems from the mid 80's. I think the design had been pretty much changed by then - everything was microprocessor based.
Posted 24 August 2012 - 07:09 PM
- Ring/Tip -- from the CO/FXS/ATA
- A/A1 -- Closed when a line key is closed
- L/LG -- Illuminates the lamp for a key
That repeats for as many lines as the phone will handle. Just driving the lamps would be pretty simple, but I'll have to see if I can come up with something a little more involved.
Posted 24 August 2012 - 07:41 PM
Posted 24 August 2012 - 07:57 PM
Incidentally, I think I've actually got a 400-series KSU card. I picked it up at the MIT Flea because it had a really unusual metal can LED on it (and it was $0.50), but it looks a /lot/ like a 1:1 clone of ITT's 400 series card. I'll have to see if I can trace the circuit out well enough to confirm that (or just power it up and see if it smokes...I do know it's out of an old PBX).
Posted 24 August 2012 - 08:12 PM
Posted 27 August 2012 - 02:17 PM
Yup, I'd come across their resources in Googling around -- good stuff!
In case you haven't seen this site, do a CTRL+F for "key" and you'll find several documents that may be helpful:
I picked up a Western Electric 1A2 5-line key phone today, so experimenting will commence once it arrives. I've also got two known-good K400D line modules on the way (apparently only $1 each on eBay) -- shouldn't be hard to provide a breakout and power supplies for the modules, and build a solid-state interruptor for flashing lamps. I'd like to find a real Bell System KSU at some point though.
Posted 06 September 2012 - 08:23 AM
I've been reading over the BSP for the phone...very good stuff. In addition to switching multiple lines to a handset and providing visual indication, you can remove a screw on the PU buttons and use them as momentary push without affecting the selected line. Of course, you can control each lamp independently. Screw terminals and a socket are also provided for the usually-nonilluminated red HOLD button, which will most likely get used as a MWI.
Posted 06 September 2012 - 09:15 PM
I'd like to find a real Bell System KSU at some point though.
Ask around your local communications companies. When I did that sort of thing not too long ago, we had lots of customers who were pulling those things out and dumpstering them, especially when remodeling the building.
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