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Posted by David Lesher on August 19, 2007, 11:06 pm
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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 house
where 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 magnetic
design, etc...
The explanation had to do with the issue of coupling enough energy down
a twisted pair tens of thousands of feet long, with 2R series resistance
and Xc capacitive reactance shunting things.
I have no idea where I read this; it could have even been a Larry Lippman
post, but I don't find anything in a brief search.
Does anyone here recall something on this?
--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433
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Posted by ChairmanOfTheBored on August 19, 2007, 11:14 pm
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wrote:
>The explanation had to do with the issue of coupling enough energy down
>a twisted pair tens of thousands of feet long, with 2R series resistance
>and Xc capacitive reactance shunting things.
>
>I have no idea where I read this; it could have even been a Larry Lippman
>post, but I don't find anything in a brief search.
>
>Does anyone here recall something on this?
Sure, that's what it was about. That was also why all phones at one's
house had to be declared, and their "ringer equivalency number" and
ampere rating. Folks at the very end of a such a line didn't have much
juice left to actually actuate the ringer, which was an electro-magnet
pulling a flat plate against the end of the coil/pole combo, then
releasing it. The bell rang one tone on the pull, which required the
power, and ALWAYS would ring the other on release.
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Posted by T on August 20, 2007, 7:40 pm
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RUBored@crackasmile.org says...
> wrote:
>
> >The explanation had to do with the issue of coupling enough energy down
> >a twisted pair tens of thousands of feet long, with 2R series resistance
> >and Xc capacitive reactance shunting things.
> >
> >I have no idea where I read this; it could have even been a Larry Lippman
> >post, but I don't find anything in a brief search.
> >
> >Does anyone here recall something on this?
>
>
> Sure, that's what it was about. That was also why all phones at one's
> house had to be declared, and their "ringer equivalency number" and
> ampere rating. Folks at the very end of a such a line didn't have much
> juice left to actually actuate the ringer, which was an electro-magnet
> pulling a flat plate against the end of the coil/pole combo, then
> releasing it. The bell rang one tone on the pull, which required the
> power, and ALWAYS would ring the other on release.
>
And that very same 90VAC 20Hz ring signal meant that the first
electronic switching system deployed in Morris, IL need custom phones
with electronic ringer because the gas tubes couldn't handle the high
voltage necessary to pass ring. They overcame that with the Remendur
switches but it took time.
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Posted by Terry on August 20, 2007, 9:01 pm
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>
> 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 house
> where 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 magnetic
> design, etc...
>
> The explanation had to do with the issue of coupling enough energy down
> a twisted pair tens of thousands of feet long, with 2R series resistance
> and Xc capacitive reactance shunting things.
>
> I have no idea where I read this; it could have even been a Larry Lippman
> post, but I don't find anything in a brief search.
>
> Does anyone here recall something on this?
>
The stuff I have always worked with was 48vdc and 90vac, and the 90vac was
not always sinusoidal, but close.
TerryS
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Posted by David Lesher on August 21, 2007, 1:47 am
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>The stuff I have always worked with was 48vdc and 90vac, and the 90vac was
>not always sinusoidal, but close.
Well, in theory 48V, [my typo..] but in reality above that in float, and
even more in equalize...
My SubCycle provides ~110Vrms unloaded....
--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433
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