[time-nuts] Re: Crazy Clock

[Bob Camp]

Hi


> On Dec 15, 2022, at 7:57 PM, Lux, Jim via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> On 12/15/22 9:57 AM, Alexander Huemer via time-nuts wrote:
>> As pointed out by other people already, there are several analog wall
>> clocks out there that can be set by external means like NTP, GPS, etc.
>> In my mind they all suffer from the same flaw, which is their
>> functionality is restricted to advancing time in precise increments but
>> don't "know the time". I.e. if power goes away and comes back, you'll
>> have to set such clocks by hand, even though their motor function can be
>> influenced. What is lacking is a set of 3 absolute position rotary
>> encoders with 6° resolution like described at [1] which referenced [2].
>> Somebody^{TM} should put such a clock together. 3 such encoders, a
>> stepper motor with gears to arrive at 6°, the rest is just software.
>> 
>> -Alex OE2AHL
> 
> 
> There are clocks that pulse forward with one polarity, and reset to "top of the hour or day" with a negative pulse.  My middle school had them in the 1970s, and it was interesting to watch the reset cycle (at noon).  Or, to be honest, it might be some sort of "power switching" protocol. That is, use 60 Hz to run, but some pattern of interruption sets it to a known time.  But I remember watching the minute hand snap to 12, then advance in discrete steps.


We had a system like that in one school I was at. For whatever reason, the clock in 
one room always went insane at least once a week. It loved to do this in the middle of
class. Needless to say, all focus on learning went away when the clock started wildly
spinning through however many hours or minutes it though it needed to ….

Turns out they very much do still make those clocks, mechanical solenoids and all. 
Slam them with some number of seconds of 24V or 110V AC on that solenoid and
they reset this or that way. Multiple systems came from all sorts of outfits and spares
still get made to match up with them. 

I “discovered” that 110V signaling is something to be avoided pretty early on. I would
prefer to avoid that if I can for this project. That said, I’ll always remember the IBM clock 
on the wall in 8th grade English class ….

Bob

> 
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