Re: Noises in phone line when no phones are in use
- From: "Arfa Daily" <arfa.daily@xxxxxxxxxxxx>
- Date: Wed, 17 Jan 2007 00:23:55 GMT
"Bob Shuman" <no_spam_thx@xxxxxxxxxxxxx> wrote in message
news:aqdrh.20564$yC5.10242@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Arfa,Bob, you are quite right - fingers running, brain out of gear - I must be
Nice summary. I agree with nearly everything you wrote, except, that in
the US, the ringing voltage can actually be considerably higher than 90V
peak since the legacy Telco spec calls for "less than 100VAC RMS" (more
typically 40-75V RMS as you have stated).
This translates to a "peak" of 141 volts across the incoming tip and ring.
Also, since there is always a nominal -48VDC (-52VDC maximum)
bias/battery, the absolute peak voltage relative to earth ground can
actually reach -193 volts (-52VDC - 141 volts peak)!
Bob
"Arfa Daily" <arfa.daily@xxxxxxxxxxxx> wrote in message
news:MPUqh.65526$n36.20346@xxxxxxxxxxxxxxxxxxxxxxx
For a start, there are several tens of volts across the line in its idle
state. This increases to around 90v peak when a ring signal appears
across the line.
getting old ... !! 90 volts ring signal was the figure in my head, but that
is of course, as you say AC RMS max spec, not peak. Thanks for putting me
straight d;~}
Arfa
.
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