[time-nuts] Mechanical clock sound pickup circuit

[Dave Martindale]

Someone is in the process of writing open-source watch timing software.
You may want to look into it.

It was announced here:
http://forums.watchuseek.com/f6/open-source-timing-software-2542874-post21977314.html#poststop

It contains these links:
First the goodies. Here are Windows binaries
http://ciovil.li/tg.zip
and here is the full source code
https://github.com/vacaboja/tg

Apparently this software is better at dealing with noisy signals from
microphones than Biburo.  Since it's open source, you can see what it's
doing internally.  It expects an analog input, and does its own filtering
to find the interesting edges within the sound of each tick.

The precision with which you can time events is likely to be limited by the
frequency response of your sensor and the amplifier.  If that's limited to
20 kHz, a standard PC sound card is adequate.  For up to 80 kHz or so, you
can buy a relatively inexpensive USB "audio interface" that digitizes at
192 kHz (typically 24 bit resolution).  At somewhat higher cost, you can
get professional audio interfaces that accept an external clock source.

- Dave


On Fri, 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
>
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