[GTALUG] mysterious restarts

[James Knott]

On 06/27/2016 09:12 AM, Russell Reiter wrote:
>
> On Jun 26, 2016 12:14 PM, "James Knott via talk" <talk at gtalug.org
> <mailto:talk at gtalug.org>> wrote:
> <snip>
> > I don't know what power is provided on dry loops, but I believe there's
> > still "battery" on the line.  On a
>
> You put the word battery in quotes. Perhaps you mean a Rogers valve? I
> think that's how the patent names it. When I was a kid every corner
> store had a tube tester for DIY repairs.
>

That's what it's generally called.  The power comes from rectifiers,
with batteries float charging.  It's nominally -48V, but actually about -56V
>
> Anecdotally I remember CFRB as Canada's First Rogers Battery?
>

Batteryless.  Prior to that, vacuum tubes required batteries to power
the filament (heater), as there was no separate cathode.  With a
separate cathode and filament, it became possible to use AC power for
the filament, generally provided by a transformer.

> The Rogers valve was what allowed a radio to run on home current.
>

Actually, it allowed the tube filaments to run on AC.  The rest of the
radio was quite capable of running on household AC, after rectification
and filtering.  Back in those days, you'd have an AC powered radio, with
a battery used only for the filament.  Going way back, there were indeed
separate batteries for the high voltage applied to the plate, low
voltage for the filament and, in some cases, even the grid, which
required a negative bias voltage.  As technology advanced, it was
possible to add a resistor in the cathode circuit to create the negative
bias on the grid, then the separate cathode and filament allowed getting
rid of the filament battery.
>
> regular phone line, if the device
> > draws enough current, the exchange will consider the line "seized" and
> > not send ringing current on it.  If not enough current is drawn, then
> > ringing is possible.
> >
> > > I don't know for sure myself. I always assume the last quarter mile is
> > > analog, but that may have changed for newer condo and residential home
> > > development.
> > >
> > >
> > What's generally referred to as the "last mile" can be anything from
> > right next door to several kilometres.  For examples, in an apartment I
> > used to rent, the exchange was just a block away.  Here, a couple of
> > blocks.  When I was a kid, growing up in Oakville, it was about 3-4 Km
> > and it may be much further elsewhere.
> >
> > BTW, many years ago, before amplifiers, it was possible to make a call
> > from New York to Colorado, before it became too weak.
>
> Wow you look a lot younger in your picture. :-)
>

I have long been interested in the history of telecommunications, an
industry where I have spent most of my career.