Greg:
Some random thoughts:
I'm not sure why that other fellow felt the need to curse out Jeff for being enthusiastic about your project. That said, I am intrigued by it. I don't find any part that's bovine excrement.
Have you, by any chance, taken a look at the "KSU-less" version of 1A2 that is used in the ComKey 416 system?
There is a 5th line add-on box that contains the electronics to provide "one more" CO line to a system that already is using its maximum of 4 lines. I have a spare if you'd like to hold one in person and see what makes it go.
You are correct in your discovery that 20Hz sounds much nicer than 30Hz. Thirty is used in subscriber key equipment power units because it's easier (cheaper) to derive than the "better" 20 Hz, used in PBX's and CO's. Cord board buzzers in models 550, 551 and 555, especially, sound so much better when powered by 20Hz. It produces a nice purr.
The Black Magic® 20Hz supplies are powered by a 5-volt input. I may have seen some whose inputs were (ISTR) 12, 24 and/or 48 Vdc.
It's too bad that you're not closer to Lancaster, PA, where, in June of every year, a hundred or so telephone collectors, and especially, "switchers" gather to display and play with their home-brew PBX and key system equipment. We are all members of C*NET. Check out
www.CKTS.info.I'd be delighted to speak to you privately about your project and a few of mine.
PSTN : 631-sevin for nyne-0100
C*NET: 1+ sevin for nyne-0100
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