[time-nuts] How did they distribute time in the old days?

Adrian Godwin artgodwin at gmail.com
Fri Oct 16 07:38:46 EDT 2015


I have a synchronome clock built for the British Post Office.

I find that the 10V or so that a USB to serial adapter can produce can
trigger the solenoid, if allowed to charge a capacitor for the intervening
minute. The effect is that I can print a single character once a minute at
a low bit rate and, with a few components but no power supply beyond USB,
step the clock.

A better solution would include a microcontroller to remember where the
hands had stepped to, for automatic recovery after a stoppage.


On Fri, Oct 16, 2015 at 1:25 AM, Brooke Clarke <brooke at pacific.net> wrote:

> Hi Don:
>
> I've got a number of SWCC clocks and 3V doesn't work for any of them.
> I've done a number of experiments and a higher voltage and series resistor
> makes a huge improvement.
>
>
> Mail_Attachment --
> Have Fun,
>
> Brooke Clarke
> http://www.PRC68.com
> http://www.end2partygovernment.com/2012Issues.html
> http://www.prc68.com/I/DietNutrition.html
> Don Couch wrote:
>
>> Hi, Brooke,
>>
>> My self winding clock synchronizes fine on three volts. I built a
>> synchronizer using a PIC controller with a 32KHz quartz crystal, running on
>> three volts. You might want to carefully check the coil and connections on
>> yours. By the way, the winding coils also are running on three volts.
>>
>> Don Couch
>>
>> On 10/14/2015 11:02 AM, Brooke Clarke wrote:
>>
>>> Hi Nick:
>>>
>>> One of my Self Winding Clock Co. (WU) clocks was taken down yesterday
>>> for painting.
>>> When put up one of the Ken's Clock Synchronizers was installed and the
>>> hands moved to align with the heart shaped cam it uses, but it never worked.
>>> The problem was it used a 4.5 Volt signal which can develop the current
>>> needed to pull the sync electromagnet the time constant is far too slow.
>>> I'm going to add a high voltage circuit with series resistor to get the
>>> time constant down one or two orders of magnitude.  The key to this is a
>>> PCB I make that holds 5 each 9V batteries connected in series, so I'll use
>>> one, two or more of them to get the time constant down.
>>> http://www.prc68.com/P/45VS.html
>>>
>>> Before I had the 45 Volt Stick I was considering getting the needed high
>>> voltage by charging a cap a minute or two before the top of the hour and
>>> discharging it through a resistor.  Here's a video showing that would work.
>>> http://www.prc68.com/I/SWCC.shtml#Experiments_Feb_2014_
>>>
>>> Mail_Attachment --
>>> Have Fun,
>>>
>>> Brooke Clarke
>>> http://www.PRC68.com
>>> http://www.end2partygovernment.com/2012Issues.html
>>> http://www.prc68.com/I/DietNutrition.html
>>> Nick Sayer via time-nuts wrote:
>>>
>>>> On Oct 14, 2015, at 4:42 AM, billriches <bill.riches at verizon.net>
>>>>> wrote:
>>>>>
>>>>> Not milisecond time distribution but time related!
>>>>>
>>>>> In the early half of the 1900s Western Union was in the time
>>>>> business.  They
>>>>> would rent businesses such as banks, office buildings, etc clocks for
>>>>> a few
>>>>> dollars a month.  These were pendulum wall clocks that had 2 #6 dry
>>>>> cell
>>>>> batteries inside that would wind them every hour or so. The clocks were
>>>>> connected to the WU telegraph line and for a minute before and after
>>>>> the
>>>>> top of the hour all traffic on the circuit would stop. Exactly at the
>>>>> top
>>>>> of the hour they would push a pulse of 50 ? volts or so over the line
>>>>> and it
>>>>> would reset the clock to the top of the hour.
>>>>>
>>>> The WU standard time service goes back further than the turn of the
>>>> 20th century. It started in 1870.
>>>>
>>>> I’ve always wanted to get my hands on one of those clocks and come up
>>>> with a circuit to recreate the synchronization signal for it, probably with
>>>> a Raspberry Pi running ntpd and a big ol’ MOSFET. The problem is that at
>>>> this point, those clocks are quite expensive once they’re reconditioned.
>>>>
>>>> My understanding (perhaps incorrect) was that the sync pulse was once
>>>> daily and, as you said, would cause the hands to “snap” to 12. The trailing
>>>> edge of the pulse was synchronized and would release the clock to operate
>>>> normally.
>>>>
>>>> That they had something as accurate and widespread as it was so early
>>>> is astonishing.
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>>>>
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