[time-nuts] Synchronisation of crystal oscillators

[Bob kb8tq]

Hi

The correct answer is “that depends”. The quick answer is “probably will”.

It depends on the Q of the parts (which likely is pretty low), the coupling 
(which will be pretty good), and the exact frequency of each unit (which is 
unknown). Setups like this have been known to lock up.

Bob

> On Mar 1, 2020, at 5:28 PM, John Moran, Scawby Design <john at scawbydesign.co.uk> wrote:
> 
> My apologies if this is slightly off-topic, but it does concern crystal oscillators.
> 
> I have a small collection of ancient crystals amassed over the past 50 years or so. Half a dozen are low frequency (3,600Hz, 10kHz,  and 100kHz), long bar, crystals sealed into B7G vacuum tube bodies. I was considering mounting them all in a neat row in a nice aluminium housing with individual oscillator circuitry and LDO regulators to ensure that they were all independent. For fun I will divide each oscillator down to 1PPS and use that the flash individual LEDs in the face of the housing, and watch them all slowly move in and out of phase with each other.
> 
> However, I then remembered Huygens's discovery that 1S pendulums mounted on the same wall, or beam, would synchronise and swing either in phase, or out of phase and sometimes one would be stopped, by the minute interactions.
> 
> So, my question is - will my row of low frequency crystals 'talk' to each other and synchronise in their frequency groups as well? Remember that these crystals are long thin bars of quartz - one of the 3,600Hz crystals being 2mm square by 60mm long - so they will possibly vibrate quite vigorously compared with squat discs.
> 
> I look forward to your comments.
> 
> John
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