[time-nuts] Regulating a pendulum clock (Jim Palfreyman)

[mike cook]

Check out Bryan Mumfords page.  
http://www.bmumford.com/clocks/em2/index.html

Le 08/08/2010 11:14, Steve Rooke a écrit :
> I was rather more thinking of the setup that Don was suggesting as not
> many domestic clocks have a seconds pendulum and it would otherwise
> take dividing down a referenced oscillator to the correct frequency.
>
> Cheers,
> Steve
>
> On 08/08/2010, Neville Michie<namichie at gmail.com>  wrote:
>    
>> Not many clocks are set up with the gear to modulate the rate,
>> but they are all still sensitive to injection locking.
>> A tiny rare earth magnet on the pendulum (say 1/2 way down the
>> pendulum rod)
>> and a coil fed with a stretched (say 250ms long) PPS or for a seconds
>> pendulum
>> PP2S pulse will pull the pendulum into phaselock with a surprisingly
>> small amount of power.
>> In fact if you turn off the drive it would keep the pendulum swinging.
>> Cheers, Neville Michie
>>
>> On 08/08/2010, at 6:00 PM, Steve Rooke wrote:
>>
>>      
>>> This is very interesting and I wonder if the capabilities of this
>>> system being applied to any clock pendulum. If this sort of control
>>> any pendulum, then I wonder if it's possible to sync it to some
>>> standard.
>>>
>>> Steve
>>>
>>> On 08/08/2010, Don Mimlitch<donmeis at yahoo.com>  wrote:
>>>        
>>>> Jim Said:
>>>>          
>>>>> It also has a coil mounted near the pendulum and a fixed magnet
>>>>> on the
>>>>> pendulum bar and this coil connects to a box down below with a meter
>>>>> and a knob. They are labeled in sec/day. The electronics in the box
>>>>> are not clear (being quite old) but by measuring the current in the
>>>>> coil it quite simply increases the current one way to slow the clock
>>>>> and the other way to speed it up. (I'll admit the physics of this
>>>>> doesn't make sense to me - but it works!)
>>>>>            
>>>> I have a Warren Telechron Master Clock used in Power Stations in
>>>> the 20's to
>>>> regulate the 60 Cycle so that household clocks using synchronous
>>>> motors
>>>> would be accurate to seconds a day.
>>>>
>>>> This clock has a similar permanent magnet at the end of the
>>>> Pendulum and
>>>> a battery connected to a potentiometer to adjust the current flow
>>>> positive
>>>> or negative in an electro-magnet below the pendulum..
>>>> If the bottom of the magnet in the pendulum is "north" and the
>>>> current in
>>>> the electromagnet is flowing such that its top face is North, then
>>>> this will
>>>> repel the pendulum causing its swing to be wider and contrary to
>>>> common
>>>> knowledge the swing of a fixed length pendulum is not constant
>>>> regardless of
>>>> the swing. (Huygens discovered this in 1670 an found by forcing
>>>> the arc of
>>>> the swing to be cycloid instead of circular he could produce uniform
>>>> oscillation) Thus if the arc is longer the swing takes more time
>>>> and the
>>>> clock runs slower.
>>>> If the current flows in the opposite direction and the two magnets
>>>> attract
>>>> then the arc is shortened and the clock runs faster. Of course my
>>>> master
>>>> clock isn't as accurate as a Riefler pendulum clock. Also the
>>>> magnet in my
>>>> clock has lost it's magnetism over time and I can't use this
>>>> regulation.
>>>>
>>>> So the goal of your adaptation is to have precision control of the
>>>> current
>>>> flow in the positive or negative direction. Others on the list are
>>>> better
>>>> then me at describing how you might achieve this.
>>>>
>>>>
>>>>
>>>>
>>>>
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>>>>          
>>>
>>> --
>>> Steve Rooke - ZL3TUV&  G8KVD
>>> The only reason for time is so that everything doesn't happen at once.
>>> - Einstein
>>>
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>>>        
>>
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>
>