[time-nuts] Mechanical clock sound pickup circuit

[Bob Camp]

HI

You *may* find that moving the passband of the mic up above 4 KHz helps things a bit. 
An analog high pass filter that rejects normal speech and low frequency rumble ahead of the detection
process wold be the old school way to do it. 

The degree to which that helps depends a bit on the tick that your escarpment makes. There is no
real guarantee that it’s got energy up above 4 KHz. They often do, but that’s not a guarantee. 

Bob

> On Dec 11, 2015, at 1:44 PM, Andrea Baldoni <erm1eaae7 at ermione.com> wrote:
> 
> Hello!
> 
> I decided to do some experiments with mechanical clocks, so I worked a little
> on picking up escapement ticking sound, with the idea of processing it and
> obtaining a "clean" digital pulse to feed a counter.
> 
> So far, I have not yet been able to find the best way to obtain a digital pulse,
> but I have already built the preamp for the piezoelectrick pickup, that
> I used to feed the mic input of a PC sound card for spectrum analysis.
> 
> The timing could eventually be done in software because the whole idea of
> measuring watches by picking up their noise almost surely doesn't allow high
> resolution anyway, but I will plan to try hardware solutions as well in the
> future. I hope to be able to measure the jitter of the clock, but it will be
> very hard.
> 
> In the meantime, with the free software Biburo you can download here
> 
> http://tokeiyade.michikusa.jp
> 
> you can regulate your wrist watch.
> 
> Best regards,
> Andrea Baldoni
> <watch_preamp.jpg>_______________________________________________
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