[time-nuts] Mechanical clock sound pickup circuit
azelio.boriani at gmail.com
Sun Dec 13 12:40:55 EST 2015
Maybe this can be useful to make the pick-up:
they can be found also on the usual auction site.
On Sat, Dec 12, 2015 at 10:28 PM, Alexander Pummer <alexpcs at ieee.org> wrote:
> Once upon the time there was a "Vibrograph", see nice pictures here:
> ,which picked up the sound of watches, clocks, and the watch maker was able
> to set the watch very accurately, these machines did not used any fancy DSP
> despite that they worked very well, I myself used one some 55 years ego in
> to get a reliable digital signal from a noisy analog signal is the most
> reliable way to use an analog PLL with a linear multiplier type phase
> detector [ at least one input of the phase detector must be linear e.g. a
> transitional gate [cd4016 and it's derivatives ], the noise could be
> filtered out with a low pass filter or integrator, the price of the method
> is that it also eliminates the phase-noise of the the input signal, .
> That was the method which was used by the Vibrograph.
> On 12/12/2015 7:15 AM, Dave Martindale wrote:
>> Someone is in the process of writing open-source watch timing software.
>> You may want to look into it.
>> It was announced here:
>> It contains these links:
>> First the goodies. Here are Windows binaries
>> and here is the full source code
>> 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
>> 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>
>>> I decided to do some experiments with mechanical clocks, so I worked a
>>> on picking up escapement ticking sound, with the idea of processing it
>>> 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
>>> 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
>>> resolution anyway, but I will plan to try hardware solutions as well in
>>> future. I hope to be able to measure the jitter of the clock, but it will
>>> very hard.
>>> In the meantime, with the free software Biburo you can download here
>>> you can regulate your wrist watch.
>>> Best regards,
>>> Andrea Baldoni
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