Telephone Ringers: how & why

David Lesher · 2007-08-20T03:06:17+00:00

Years ago, I read an explanation of why telco ringers are what they are.[Or ...were..., now that we are doomed to tweedlers...except @ my housewhere the 2565 lives on forever...]Yea, we know that they are typically 20hz, sinusoidal waveform, ~120VAC RMS atop 45VDC....But... the WHY behind those decisions was illuminating. After all,there's a fair chunk of change in that dual gong ringer's magneticdesign, etc...The explanation had to do with the issue of coupling enough energy downa twisted pair tens of thousands of feet long, with 2R series resistanceand Xc capacitive reactance shunting things.I have no idea where I read this; it could have even been a Larry Lippmanpost, but I don't find anything in a brief search.Does anyone here recall something on this?

Aug 20, 2007 63 Replies

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T 19 years ago

I'm fully aware of those facts. All I'm trying to say is that there's a lot of energy floating around out there that we can't even begin to tap into.

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David Lesher 19 years ago

Another aspect.... sealing current implies DC continuity.

That makes craft level loop testing far easier. Larry Lippman made a long post detailing the various bridges [Whetstone, etc] the Test Board used to find where the fault was, but I can't find it in the Google archives.

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