In article <telecom24.228.14@telecom-digest.org>,
> [TELECOM Digest Editor's Note: City of Chicago used DC power (rather
> than AC) -- at least in the downtown area -- until sometime around
> 1930. That's at least one reason why there were so many WUTCO clocks
> everywhere, instead of 'regular' wall clocks. Clocks cannot run on
> direct current; they require alternating current at 60 cycles.
I wonder what they did in territory where the generated A.C. power was
at 25 cycles.
Or how a battery-operated clock works. <grin>
The design _is_ significantly different, because you don't have the
'frequency standard' of the A.C. power to stabilize the timing,
A D.C. powered clock has to employ some other form of a 'regulator'
mechanism, rather than relying on the power-line. This is typically a
pendulum, or a 'balance wheel', controlling an 'escapement' mechanism.
Basically identical to that of a wind-up clock, just using the
power-line to keep the mainspring wound up.
A.C. powered designs _are_ 'simpler'. And *MUCH* easier to ensure
that multiple clocks keep the same 'rate' of time -- they all link
back to the same *single* timing source, the power utility. With
D.C. clocks, you have to adjust the 'regulation' on each one,
independently. Politely described as a pain in the nether portions of
the anatomy. :)
[TELECOM Digest Editor's Note: I will confine my remarks to only your
comment on 'how a battery operated clock works' <with a big grin
right back at you>. See my earlier message to Daryl. Wall clocks for
example, use the battery to wind the mainspring only. If this were
not so, then as the battery ran down, the clock would run slower and
slower wouldn't it? Most wall clocks keep on running as long as the
battery has the necessary 'juice' to continue winding the spring, and
you may note that when the battery begins to get weak, the spring
takes a couple seconds longer to wind, but wind it does, and that
is what keeps the clock hands moving, _not_ the battery. Truely, when
the 'battery runs out' the clock also within a minute or two will
stop, but the two events are not connected. You could reach in the
back of the battery operated wall clock and rewind the spring by
hand. And a true electrical clock does not have to be mounted in a
level way; you lay it upside down on the floor for all anyone cared;
if plugged in it would continue to run correctly. But try that with
a battery/spring wound clock (not having it hung level on a flat
surface.) PAT]
Robert Bonomi (bonomi@host122.r-bonomi.com)