Author Topic: Cheapo clock tear up.  (Read 7208 times)

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Offline DrGTopic starter

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Cheapo clock tear up.
« on: January 04, 2022, 06:51:54 pm »
I used to use an old style, “analog” wall clock. It was definitely inexpensive and did not keep time particularly well. Purchased some ~20 years ago, it eventually found its way into storage (and yes, I did remove the battery first).  It worked, more or less, and had served its purpose.

For some reason, I decided that I wanted to once again use that old style clock face. So, I took it out and inserted a fresh battery and…nothing.



Investigating further, I quickly found the culprit – oxidation on the (-) terminal. Scraping that off, resolved the problem and I could see the pulsing gear movement.



That first gear, nearest the coil, has a magnet inside. I removed it from its place and inverted it in the picture.



So, the circuitry under the blob, amplifies the crystal oscillation pulses to drive the coil – right? Nice little neat design.

These are more interesting electronically than I had realized, but then again, I am easily amused sometimes.

I still will reinstate an old style face clock, but not this one. Instead I ordered another https://www.amazon.com/Crosse-Technology-WT-3102S-Silver-Atomic/dp/B000AMCAUG with radio setting. I have a wrist-watch with such a receiver that does, in fact, work well enough to never have to set. I am hoping that this one will be as good.
« Last Edit: January 04, 2022, 06:54:15 pm by DrG »
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Offline BrokenYugo

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Re: Cheapo clock tear up.
« Reply #1 on: January 04, 2022, 07:07:32 pm »
Pretty close, the crystal runs at ~32768Hz (215), which conveniently divides down to 1 pulse per second with simple divide by two logic, that is then amplified to drive the stepper motor.
 
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Offline DrGTopic starter

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Re: Cheapo clock tear up.
« Reply #2 on: January 04, 2022, 07:29:14 pm »
No, I don't think you got that right at all. Not about the crystal, about a stepper motor. That gear is not attached to the shaft of a motor. There is no stepper motor or motor at all. Movement is accomplished by two magnets. One is a permanent magnet inside the base of that first gear. The other is an electromagnet (i.e., that coil). Energizing the coil creates a repelling magnetic pulse that moves the gear - perhaps my non-EE terms leave something to be desired.

So, beyond the crystal oscillator, it would seem that electromagnet pulse width needs to be fairly precisely specified so that only a single gear-tooth move is produced - that is what I think is so neat.

EDIT: Also, I really don't want this to be an argument thread or, just as bad, an "I know more than you thread so I am going to correct you". I think I have the operation of this right. If you KNOW you have it right than feel free to explain and all will benefit. But, please, appreciate that I went through the trouble of taking and posting pictures of something that I though was interesting and entertaining.
« Last Edit: January 04, 2022, 07:39:12 pm by DrG »
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Offline Ian.M

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Re: Cheapo clock tear up.
« Reply #3 on: January 04, 2022, 07:42:30 pm »
Its a single coil stepper.  The magnet aligns with the coil's core poles.   Reverse the coil drive and the magnet will turn to align its next pole, overshooting slightly due to inertia.   Somewhere in the mechanism there will be some sort of ratchet or friction clutch device that prevents it running back to bring the magnet in exact alignment with the core poles, so that the direction is predictable.

If the mechanism is otherwise in decent condition, that would be a good candidate to convert to a Vetinari clock.

The higher supply voltage will overcome any slight stickiness in the mechanism  and you can compensate for the crystal's measured frequency error in the code.

GNU Pterry
« Last Edit: January 04, 2022, 08:20:27 pm by Ian.M »
 
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Offline DrGTopic starter

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Re: Cheapo clock tear up.
« Reply #4 on: January 04, 2022, 08:01:48 pm »
Its a single coil stepper.  The magnet aligns with the coil's core poles.   Reverse the coil drive and the magnet will turn to align its next pole, overshooting slightly due to inertia.   Somewhere in the mechanism there will be some sort of ratchet or friction clutch device that prevents it running back to bring the magnet in exact alignment with the core poles, so that the direction is predictable.

If the mechanism is otherwise in decent condition, that would be a good candidate to convert to a Vetinari clock.  The higher supply voltage will overcome any slight stickiness in the mechanism  and you can compensate for the crystal's measured frequency error in the code.

GNU Pterry

Ohhh ok, I gottya, what you are saying is "Movement is accomplished by two magnets. One is a permanent magnet inside the base of that first gear. The other is an electromagnet (i.e., that coil). Energizing the coil creates a repelling magnetic pulse that moves the gear"- thanks so much for the official explanation :)
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Offline Benta

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Re: Cheapo clock tear up.
« Reply #5 on: January 04, 2022, 08:04:38 pm »
Its a single coil stepper.  The magnet aligns with the coil's core poles.   Reverse the coil drive and the magnet will turn to align its next pole, overshooting slightly due to inertia.   Somewhere in the mechanism there will be some sort of ratchet or friction clutch device that prevents it running back to bring the magnet in exact alignment with the core poles, so that the direction is predictable.

^ This.
Except that the permanent magnet poles will be 90 degrees offset from the two coil poles by the ratchet.
The ratchet mechanism can be seen on the third gear wheel (the two crescent-shaped thingys with a hook at the end).
« Last Edit: January 04, 2022, 08:13:01 pm by Benta »
 

Offline DrGTopic starter

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Re: Cheapo clock tear up.
« Reply #6 on: January 04, 2022, 08:15:29 pm »
Its a single coil stepper.  The magnet aligns with the coil's core poles.   Reverse the coil drive and the magnet will turn to align its next pole, overshooting slightly due to inertia.   Somewhere in the mechanism there will be some sort of ratchet or friction clutch device that prevents it running back to bring the magnet in exact alignment with the core poles, so that the direction is predictable.

^ This.
Except that the permanent magnet poles will be 90 degrees offset from the two coil poles.
The ratchet mechanism can be seen on the third gear wheel (the two crescent-shaped thingys with a hook at the end).

OK, thanks, I must have been on drugs to think that "Movement is accomplished by two magnets. One is a permanent magnet inside the base of that first gear. The other is an electromagnet (i.e., that coil). Energizing the coil creates a repelling magnetic pulse that moves the gear"

So glad nobody validates that position... JFC sometimes you nerds...I'll tell ya  :-DD
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Offline BrokenYugo

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Offline DrGTopic starter

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Re: Cheapo clock tear up.
« Reply #8 on: January 04, 2022, 08:49:48 pm »
https://en.wikipedia.org/wiki/Lavet-type_stepping_motor

Pretty close.

Please explain why "Movement is accomplished by two magnets. One is a permanent magnet inside the base of that first gear. The other is an electromagnet (i.e., that coil). Energizing the coil creates a repelling magnetic pulse that moves the gear" is incorrect. Thanks, I notice that was missing. Third time I am asking in the thread....Beuler...beuler..


Please read this link:
https://www.psychologytoday.com/us/blog/shift-mind/201103/why-is-it-so-important-be-right

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Offline Benta

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Re: Cheapo clock tear up.
« Reply #9 on: January 04, 2022, 09:16:54 pm »
Erm... puts on hat and leaves (not tin foil, but Borsalino).
 
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Offline DrGTopic starter

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Re: Cheapo clock tear up.
« Reply #10 on: January 04, 2022, 09:20:19 pm »
Erm... puts on hat and leaves (not tin foil, but Borsalino).

Buh-Bye - here take this link with ya...

https://www.psychologytoday.com/us/blog/addiction-and-recovery/201907/stop-seeking-validation-others
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Offline BrokenYugo

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Re: Cheapo clock tear up.
« Reply #11 on: January 04, 2022, 09:23:51 pm »
 
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Offline DrGTopic starter

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Re: Cheapo clock tear up.
« Reply #12 on: January 04, 2022, 09:33:58 pm »
/-- snip -/

Ahh yes, such a dazzling comeback - amazing, yet so predictable.... buh-bye and I know either of those links and shiny penny will keep you occupied.

Next?

Please explain why "Movement is accomplished by two magnets. One is a permanent magnet inside the base of that first gear. The other is an electromagnet (i.e., that coil). Energizing the coil creates a repelling magnetic pulse that moves the gear" is incorrect. Thanks, I notice that was missing. Fourth time I am asking in the thread.
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Offline Ian.M

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Re: Cheapo clock tear up.
« Reply #13 on: January 04, 2022, 09:38:04 pm »
[pedant] Its only repulsion for the first half of each step.  Once the rotor has moved 90 decrees. the force is better described as magnetic attraction. [/pedant]  :horse:
 
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Offline DrGTopic starter

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Re: Cheapo clock tear up.
« Reply #14 on: January 04, 2022, 10:05:02 pm »
What was said by me, was, in fact, correct and pretty much everyone around here can figure that out.

To call it a stepper motor and then a Lavet stepper motor is simple intellectualization https://www.dictionary.com/browse/intellectualization, the original response was, at best misleading and at worst just plain wrong - that is my opinion and I have yet to see anyone type anything at all in this thread to make me change my mind - and if that were to happen, I would not have any difficulty standing corrected.

Hanging your hat on trivial details which are not at issue makes it difficult to find your hat when you leave.

What I said was correct and the point is how difficult it is for the you to even admit as much - I guess I would add the "liker" who could not muster enough gonad to respond in any other way.

What I have learned is that there are many people on this forum who have a lot of expertise and it is those folks that I predominantly read and attend to - most often when I am not even in the thread. Most impressive is when they demonstrate that the expertise is accompanied by an emotional IQ above their age.

All too common is the - "I didn't really read (or think) much but I am going to jump in to correct what has been written, no matter if I don't know what I am talking about and no matter that it has already been said or anything else...I'm jumping in - no qualifications at all...just jumping in with the wishful wisdom that exists only in their minds".

When that is questioned, I understand that it is annoying and it can sting a bit, you want to jump in and tear me a new one (too late now). I am ok with that. To those folks, block me, please, I will do the same...but also please know that I wouldn't be slapping you around if I thought you were half the expert you act like you are.

If you were you could have figured out how to respond to the query, repeatedly posted, and you would understand why you should have done so.

Peace and no leaves.
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Offline Gyro

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Re: Cheapo clock tear up.
« Reply #15 on: January 04, 2022, 10:05:35 pm »
I had to replace our kitchen clock with that exact movement a few months back. The tiny plastic pivot pin on the top of that first gear had completely worn away - the shock loading of starting and stopping the second hand is quite high.
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Offline MK14

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Re: Cheapo clock tear up.
« Reply #16 on: January 04, 2022, 10:20:22 pm »
What was said by me, was, in fact, correct and pretty much everyone around here can figure that out.

Ok, let's check out your responses then. You said:

No, I don't think you got that right at all. Not about the crystal, about a stepper motor.

So you seem to be saying that you don't think it is some kind of stepper motor.

Which would seem to be in disagreement, with other posters and the wiki article.
 
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Offline DrGTopic starter

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Re: Cheapo clock tear up.
« Reply #17 on: January 04, 2022, 11:32:56 pm »
What was said by me, was, in fact, correct and pretty much everyone around here can figure that out.

Ok, let's check out your responses then. You said:

No, I don't think you got that right at all. Not about the crystal, about a stepper motor.

So you seem to be saying that you don't think it is some kind of stepper motor.

Which would seem to be in disagreement, with other posters and the wiki article.

Predictable arrogance that literally makes my point. You have nothing at all to contribute other than a ridiculous attempt to correct - that is your purpose and I seriously doubt you have ever made a living doing it.

Let's actually read what I wrote....not your cut and paste of part of what I wrote in a  pathetic attempt to ... oh nevermind, you wouldn't understand anyways.

No, I don't think you got that right at all. Not about the crystal, about a stepper motor. That gear is not attached to the shaft of a motor. There is no stepper motor or motor at all. Movement is accomplished by two magnets. One is a permanent magnet inside the base of that first gear. The other is an electromagnet (i.e., that coil). Energizing the coil creates a repelling magnetic pulse that moves the gear - perhaps my non-EE terms leave something to be desired.

So, beyond the crystal oscillator, it would seem that electromagnet pulse width needs to be fairly precisely specified so that only a single gear-tooth move is produced - that is what I think is so neat.

EDIT: Also, I really don't want this to be an argument thread or, just as bad, an "I know more than you thread so I am going to correct you". I think I have the operation of this right. If you KNOW you have it right than feel free to explain and all will benefit. But, please, appreciate that I went through the trouble of taking and posting pictures of something that I though was interesting and entertaining.

Look at the first pph:

No, I don't think you got that right at all. Not about the crystal, about a stepper motor. That gear is not attached to the shaft of a motor. There is no stepper motor or motor at all. Movement is accomplished by two magnets. One is a permanent magnet inside the base of that first gear. The other is an electromagnet (i.e., that coil). Energizing the coil creates a repelling magnetic pulse that moves the gear - perhaps my non-EE terms leave something to be desired.

Note that I said that I don't *think* he got it right - see what I did there? Let me spell it out - it says I don't think I am the smartest MFer around, but this is what I see... Then proceeded to explain clearly what I saw and I did that correctly - you just can't admit it that. You with your "seems to", have decided that ANYTHING THAT PULSES IS A STEPPER MOTOR. This ill-advised and opportunistic mischaracterization complete ignores, like your buddy, what most people on this board think of as a stepper motor. You know that and you know that is a point and one that you can't cover when you put your hat on as you leave.

Instead of anything resembling a civil response which would include ADMITTING that what I said here is absolutely correct:

"Movement is accomplished by two magnets. One is a permanent magnet inside the base of that first gear. The other is an electromagnet (i.e., that coil). Energizing the coil creates a repelling magnetic pulse that moves the gear".


There was a correction, erroneous as it is. followed up with a drive by link - the true mark of the weak-minded who have only the time to correct...in their own minds.

In my second pph...

"So, beyond the crystal oscillator, it would seem that electromagnet pulse width needs to be fairly precisely specified so that only a single gear-tooth move is produced - that is what I think is so neat."

I again am being, at least, fundamentally, accurate and am trying to set a pleasant tone.

Finally, I edited the post adding the 3rd pph because I knew it could go the way that it did. That too is not something that you "seem" to grasp.

In my original, well before your sophomoric summary of what "seems" to be.... So, the circuitry under the blob, amplifies the crystal oscillation pulses to drive the coil – right? Nice little neat design. That is absolutely true and nothing that you have said or anyone in this thread has said refutes that at all.

Now any civil response by anyone with an IQ and an EQ above that of a leafy green vegetable, and any true expert, anyone with any successful record of communication, anyone who is sincere, would have stated - YES, when you say, "Movement is accomplished by two magnets. One is a permanent magnet inside the base of that first gear. The other is an electromagnet (i.e., that coil). Energizing the coil creates a repelling magnetic pulse that moves the gear". You are correct....and....______.

That is the point - the "corrector" is not intellectually or emotionally inclined to do such a thing as it would defeat the reason they are responding in the first place.

But if you had, then you could come up with whatever contribution you wanted to add....it's a stepper motor, not in the usual sense as there is no shaft that the gear is connected to like the ones you have probably used, or...this is an old design and works so well it is all over the place, and so on and so forth.

You, again, could not do that - ask yourself why you could not do that - ask yourself why you still can't do that - I know why and sometimes I am inclined to simply call that crap out and I have already provided some drive-by links for you to go read, but, it "seems" like you disagree with them. It "seems" like you are an absolute expert on what things "seem" like. To me, it "seems" like you are just spewing disingenuous BS because you are not intellectually capable of addressing the issue in any other way.

Regardless, I can help you out by simply not responding to any more of your posts and perhaps the best thing I can tell you is that yes, I agree, to you it must *seem* like that.
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Offline MK14

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Re: Cheapo clock tear up.
« Reply #18 on: January 04, 2022, 11:47:47 pm »
Regardless, I can help you out by simply not responding to any more of your posts

 :palm:

Are they posting while drunk, too tired, had a really bad day, or something ?
« Last Edit: January 04, 2022, 11:52:11 pm by MK14 »
 
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Offline joeqsmith

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Re: Cheapo clock tear up.
« Reply #19 on: January 05, 2022, 01:56:02 am »

Offline CatalinaWOW

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Re: Cheapo clock tear up.
« Reply #20 on: January 05, 2022, 02:13:04 am »
Lots of entertainment for such a limited subject.  I have taken apart quite a few of this type of movement and the number of minor variations on the basic idea is actually kind of impressive.  Why bother looking?  Standard answer, the same curiosity that led me into an engineering career.

While I have several times contemplated programming up a micro to do some fancier functions than these things do, i just keep buying one of these movements when I want to make a clock.  They do the job very well.  In my experience they are usually accurate enough to last until the next daylight savings time forced adjustment and they are far cheaper than the pieces I would have to buy for functionality that isn't that compelling.
 

Offline edavid

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Re: Cheapo clock tear up.
« Reply #21 on: January 05, 2022, 02:54:41 am »
So, beyond the crystal oscillator, it would seem that electromagnet pulse width needs to be fairly precisely specified so that only a single gear-tooth move is produced - that is what I think is so neat.

The mechanism is designed so the pulse width doesn't matter.

Quote
Instead of anything resembling a civil response which would include ADMITTING that what I said here is absolutely correct:

"Movement is accomplished by two magnets. One is a permanent magnet inside the base of that first gear. The other is an electromagnet (i.e., that coil). Energizing the coil creates a repelling magnetic pulse that moves the gear".


I think that statement is so vague, that you can't really say it's correct or incorrect as a whole.  However, the part where you say the coil repels is incorrect, so doesn't that mean the statement is not "absolutely correct"?

Even if we agreed it was correct, I don't see how it's useful in understanding the mechanism.


 
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Offline DrGTopic starter

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Re: Cheapo clock tear up.
« Reply #22 on: January 05, 2022, 03:10:37 am »
So, beyond the crystal oscillator, it would seem that electromagnet pulse width needs to be fairly precisely specified so that only a single gear-tooth move is produced - that is what I think is so neat.

The mechanism is designed so the pulse width doesn't matter.

Quote
Instead of anything resembling a civil response which would include ADMITTING that what I said here is absolutely correct:

"Movement is accomplished by two magnets. One is a permanent magnet inside the base of that first gear. The other is an electromagnet (i.e., that coil). Energizing the coil creates a repelling magnetic pulse that moves the gear".


I think that statement is so vague, that you can't really say it's correct or incorrect as a whole.  However, the part where you say the coil repels is incorrect, so doesn't that mean the statement is not "absolutely correct"?

Even if we agreed it was correct, I don't see how it's useful in understanding the mechanism.

Well, I believe you went you say that you don't see how it is useful and that is OK, but I don't think your post is useful in understanding anything that interests me - not unlike your inability to understand that you alone are not the only one who understands that a 6501 is not the same as a 6500/01 as from your missive from a few weeks ago. Thanks so much for reminding me of your nickname.
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Offline DrGTopic starter

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Re: Cheapo clock tear up.
« Reply #23 on: January 05, 2022, 03:28:43 am »
Lots of entertainment for such a limited subject.  I have taken apart quite a few of this type of movement and the number of minor variations on the basic idea is actually kind of impressive.  Why bother looking?  Standard answer, the same curiosity that led me into an engineering career.

While I have several times contemplated programming up a micro to do some fancier functions than these things do, i just keep buying one of these movements when I want to make a clock.  They do the job very well.  In my experience they are usually accurate enough to last until the next daylight savings time forced adjustment and they are far cheaper than the pieces I would have to buy for functionality that isn't that compelling.

So happy that I could be the source of entertainment for you. I have lots of material :)  When I searched on that little clock box, I found hundreds of examples and was in the process of trying to locate the patent on this one.

One thing that I do want to comment on is your statements
Quote
Why bother looking?  Standard answer, the same curiosity that led me into an engineering career.

Now, I am not trying to insult you and I trust you know that I would not be too subtle if I were, but those statements whether intended or not, really illustrate to me, some difference between an EE and a Behavioral Scientist. Now, I am happy that curiosity about anything captured your focus, I always am happy to hear about that, assuming the curiosity was not about unscrupulous activities.

I was going to throw the clock out. It was old and crusty and somewhat yellowed. Yes, I did fix it (if you call identifying some oxidation on a contact and cleaning it off, fixing), but that was not going to rejuvenate the age and I did not care to find out if it lost even more accuracy. My point is that such an experience, for me, was driven by a simple curiosity that I have had all my life about anything and it would never inspire me to go into EE.

Instead, the pathological  behaviors (my opinion) of folks who become keyboard warriors believing that they are operating anonymously is just one of a kazillion aspects of human behavior that inspired me to go into and stay into the Neurosciences - something I have never regretted over decades of work which I call the best work a person could have - trying to understand the nervous system.

Hey, different strokes for different folks - just saying and, of course, it is what it is :)

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Offline MK14

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Re: Cheapo clock tear up.
« Reply #24 on: January 05, 2022, 03:30:25 am »
I still ask myself, why....

It is a bit like the question, does Bill Gates bother to pick up a $10 note, he accidentally drops ?
Which he got asked (or similar), and he said "He would", if I remember correctly.
I guess we learn (and/or keep in practice) from doing such repairs, and somehow it feels bad/wasteful/sinful to just throw such items away.
I'm often curious how they work. How come they are so cheap to manufacture ?
But especially, how come they manage to last, for perhaps a year, on a relatively small AA battery, despite (slowly) spinning round all those hands, throughout the year, with a (usually) inefficient motor (or stepper mechanism).
 


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