21 Feb
2007
21 Feb
'07
2:46 a.m.
From: "Chuck Guzis" <cclist at
sydex.com>
I can remember seeing at least one project for a crystal-controlled
timing source using tubes (I think it used push-pull 6F6's in the
output stage) to run an ordinary synchronous-motor wall clock. This
would probably be during the 1940s or 50s.
Does anyone remember that the oldest of said wall clocks required the
owner to start the motor manually by spinning a little knurled shaft
located on the back?
I seem to recall a rumor where the power companies were offering to replace at
no charge those clocks that needed to be mamually started (before my time.) The
reason had something to do with using power that didn't register on the power
meter. Anyone here know if this is fact or fiction?
21 Feb
21 Feb
11:30 a.m.
On Wed, 21 Feb 2007 10:46:34 +0000, Marvin Johnston wrote
I seem to recall a rumor where the power companies
were offering to
replace at no charge those clocks that needed to be mamually started
(before my time.)
Some power companies did replace clocks -- and other motor-driven appliances
-- on converting to 60Hz from, for example, the 25Hz that Niagara originally
generated.
The reason had something to do with using power
that didn't register on the power meter.
Some people find conspiracy theories attractive.
--
Kevin Schoedel <schoedel at kw.igs.net> VA3TCS
11:47 a.m.
On Wednesday 21 February 2007 14:30, schoedel at kw.igs.net wrote:
On Wed, 21 Feb 2007 10:46:34 +0000, Marvin Johnston
wrote
It's somewhat plausable; reactive power (which is part of a motor's
draw) doesn't register on the power meter, but the power company does
still pay for it, in terms of power-line losses at least. That's why
large motor installations generally have "power factor correction"
capacitors installed alongside of them.
Still, I doubt that a clock motor would have drawn enough reactive power
for the power company to notice, or even care.
Pat
--
Purdue University Research Computing --- http://www.rcac.purdue.edu/
The Computer Refuge --- http://computer-refuge.org
The reason had something to do with using power
that didn't register on the power meter.
Some people find conspiracy theories attractive. 
4:27 p.m.
>
> Does anyone remember that the oldest of said wall clocks required the
> owner to start the motor manually by spinning a little knurled shaft
> located on the back?
I've enver actually used one, but I've seen them, and read about them.
Another method that was common over here was to have a spring-loaded
lever that was operarted when you pusehd or pulled the set-hands knob to
set the time. Releasing said knob caused the lever to give a 'kick' to
the motor's rotor to get it going in the right direction. These little
synchonous motors were symmetircal and could run either way, so you might
end up with a clock that runs backwards :-).
Mroe recent clocks have a mechanism that detects if the motor is turning
backwards and if so, stop it and kick it back again, thus getting it
going the right way. On a clock fitted with a second hand, you will see
it run backwards for a few seconds sometimes when you connect it to the
mains until said device operates and getis going the right way.
I seem to recall a rumor where the power companies were offering to replace at
no charge those clocks that needed to be mamually started (before my time.) The
reason had something to do with using power that didn't register on the power
meter. Anyone here know if this is fact or fiction?
Soundsl ike fiction to me. Electricity meters, at least in the UK have
(by law) to record true power only. Now, 'reactive power' (an oxymoron
IMHO) is disliked buy the power companies because they don't get paid for
it, but the extra current does contribute to I^2R losses in the power
cables, it does mean heavier cables are needed, and so on.
But, I can't see whay yhr power factor of a self-starting clock would be
necessarily any different to that of an older clock. In any case, the
total current trhugh such a clock motor is tiny anyway, for a normal
house with a few such clocks it is not going to cause any problems.
-tony
8 Mar
8 Mar
9:25 a.m.
From: "Tony Duell" <ard at p850ug1.demon.co.uk>
I have one of the early manual start synchronous clocks running in the
lounge at this moment. It's a Ferranti clock from around 1934, and gives
very good service. It's quite happy running in either direction.
I also have an electrically re-wound clock from about 1920, which was used
as a time switch. The clock is regulated by a pendulum, but uses a large
rotary solenoid to rewind the clock about every five minutes - by using a
small proportion of the spring, the accuracy is improved, as the drive power
varies as a spring runs down, leading to inaccuracies in the timekeeping of
a simple spring driven clock.
A few other interesting timepieces about the place are a Junghan mantel
clock which uses an electrically impulsed pendulum (impulsed every swing of
the pendulum), but is fairly inaccurate, due to a short pendulum made of
steel. A GPO Clock No36, which was used in British telephone exchanges for
generating metering pulses - it is a Hipp type clock, with a 1 Second
pendulum, driven by an electromagnet, and gives out 1, 6, and 30 second
impulses. The rated accuracy is 8 seconds per week, but in practice, they
can be regulated to a better accuracy than that. Finally, there is a
Telephone Rentals master clock, which has a 1 second pendulum, and a gravity
impulse mechanism, similar to the Synchronome type (think cheap copy.....),
which is attached to a uniselector chronogram - basically a seven day time
switch made of uniselectors, allowing on and off periods to be set to an
accuracy of 1 minute anywhere in a week.
Bringing the subject back to vintage computers, my current project is to use
one of my old Vaxstations as a NTP server on my home network, coupled to a
radio clock of similar vintage.
Jim
>
> Does anyone remember that the oldest of said wall clocks required the
> owner to start the motor manually by spinning a little knurled shaft
> located on the back?
I've enver actually used one, but I've seen them, and read about them.
Another method that was common over here was to have a spring-loaded
lever that was operarted when you pusehd or pulled the set-hands knob to
set the time. Releasing said knob caused the lever to give a 'kick' to
the motor's rotor to get it going in the right direction. These little
synchonous motors were symmetircal and could run either way, so you might
end up with a clock that runs backwards :-).
Mroe recent clocks have a mechanism that detects if the motor is turning
backwards and if so, stop it and kick it back again, thus getting it
going the right way. On a clock fitted with a second hand, you will see
it run backwards for a few seconds sometimes when you connect it to the
mains until said device operates and getis going the right way.
21 Feb
21 Feb
7:51 p.m.
From: Marvin Johnston <marvin at rain.org>
Hi
As a kid, I had a motor from such a clock. The rotor was a cage of bars
that went by an electro megnet, run by AC. It would just sit and vibrate
until one gave it a start.
The shade pole motors replaced these because they'd self start. They
do use more electricity while running to induce current in the shading coil.
So, the clock runs a little hotter.
Dwight
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From: "Chuck Guzis" <cclist at
sydex.com>
I can remember seeing at least one project for a crystal-controlled
timing source using tubes (I think it used push-pull 6F6's in the
output stage) to run an ordinary synchronous-motor wall clock. This
would probably be during the 1940s or 50s.
Does anyone remember that the oldest of said wall clocks required the
owner to start the motor manually by spinning a little knurled shaft
located on the back?
I seem to recall a rumor where the power companies were offering to replace
at
no charge those clocks that needed to be mamually started (before my time.)
The
reason had something to do with using power that didn't register on the
power
meter. Anyone here know if this is fact or fiction?
6499
days inactive
6514
days old
5 comments
6 participants
participants (6)
-
ard＠p850ug1.demon.co.uk -
dkelvey＠hotmail.com -
jim＠g1jbg.co.uk -
marvin＠rain.org -
pat＠computer-refuge.org -
schoedel＠kw.igs.net