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Time Ticks Backwards on This Clock

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Beth Stackpole
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Blogger
The things we get used to
Beth Stackpole   1/6/2012 6:59:55 AM
I actually laughed out loud at this post. The fact that the clock faithfully kept time backwards for over a year and you and your wife just got used to it is hysterical, but I can totally relate. We humans are a strange breed--we get used to something and we make every concerted effort possible to work with it and make it last as long as possible.

Jennifer Campbell
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Gold
Like Clockwork
Jennifer Campbell   1/6/2012 8:35:58 AM
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I have to ask, Ralph - What finally killed the clock?

Rob Spiegel
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Re: The things we get used to
Rob Spiegel   1/6/2012 11:37:47 AM
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I agree, Beth, this is a funny one. I'm just trying to imagine what it's like to learn to read a clock that runs backwards. Then you have to wonder if that talent affects your ability to read a clock that runs forward.

Ratsky
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Platinum
Re: The things we get used to
Ratsky   1/6/2012 2:57:29 PM
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My wife and I have old friends who have a Hebrew clock, which of couse runs counter-clockwise!  The answer to this puzzle is: the old-time electric clocks used small synchronous motors.  Synchronous motors, unlike the more-common induction motors, (for those of you whose engineering education occured after the Motors and Power labs were removed from the required list of the EE curriculum) inherently are quite happy running in either direction in their most basic form.   For specific applications like these mini clock motors, the trick was to  put a small-gauge "shorted turn" winding on one side of the pole-piece gap. This would cause a small phase-shifted magnetic field which when vector-summed with the field from the main winding would result in a field that rotated synchronously (similar to that from a split-phase induction motor) that would induce a torque in tne rotor making the rotor accelerate and rotate synchronously with the field.  I suspect this winding (or in the really cheap clocks, a brass screw near the gap) may have been displaced with all the rough handling.  Thus until something made the clock start rotating in one direction or the other, it would continue in that direction as long as power was applied.  Unless the clock was powered-down with the center of the rotor exactly in the cennter of the pole gap, that would be the direction the motor would run in the next time power was reapplied.  If the rotor WAS centered, the odds were 50/50 for either direction on next power-up!

Alexander Wolfe
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Re: The things we get used to
Alexander Wolfe   1/6/2012 5:26:38 PM
Synchronous motors are a big part of the old world of audio turntables. I've restored a bunch of them, and I've found that these motors are very prone to seizing up due to dried out lubricant. (Well, not really seizing in the way an auto engine does, but getting gunked up to the point that they can't run.) Maybe that played a role here. The other thing is that when you revive them, you can't just use any old standard oil, because that will drain away too quickly. You need stuff that's not so heavy it'll inhibit motion -- these tend to be low-torque motors -- but something that'll stick around and not leak out.

Charles Murray
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New product
Charles Murray   1/6/2012 5:47:41 PM
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This could be a popular new product. Great conversation piece.

Staber Dearth
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Silver
Re: The things we get used to
Staber Dearth   1/9/2012 9:18:35 AM
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LOL!  We call this a simple "workaround" in corporatedom. Sometimes you just sidestep the disconnected and loopy corporate bullschitte to achieve the ultimate goal that you know everyone wants anyway.  No thanks for the workaround is ever granted and you don't admit it to anyone not onboard to your cause.  You just hand them the results that you gained through nbo support by them in the least. 

Essentially you are saving them from themselves while ensuring your own survival.  Once we lose this boldness and individuality in the business world we'll be cooked by the clueless and over compensated above us.  They then die too... so who is most important...hmmmm?


In politics, usually more known as a somewhat more subversive tactic employed by one side of the political spectrum moreso than the other, it is often called "justifying the means by the ends"...

alanbee
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Iron
More than one way to skin a cat
alanbee   1/9/2012 9:49:53 AM
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As a newly minted electrical engineer (back when dinosaurs ruled the eath) I was asked to debug my grandmother's alarm clock, which exhibited the same backward running behavior discussed above.  The motor was the same synchronous design, but instead of a shaded pole arrangement to provide the initial torque, this design had a small cam that acted as a one-way clutch that would mechanically stop the motor and kick it back in the right direction.  After cleaning and lubricating, it worked fine.  My folks were impressed.....

Rob Spiegel
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Re: The things we get used to
Rob Spiegel   1/9/2012 10:04:03 AM
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Good explanation, Ratsky. Does this mean that if you unplugged the clock and then plugged it back in, there is a 50/50 chance it would begin to run the right way? Could it be that this clock continued to run backwards simply because the power source continued, uninterrupted?

Quacker
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Bronze
Offensive Avatar
Quacker   1/9/2012 10:08:41 AM
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Please request that "Staber Dearth" remove his offensive avatar.

Thank you.

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