[time-nuts] Quartz assisted pendulum clock.

jayh6 at verizon.net jayh6 at verizon.net
Thu Jan 5 13:55:48 EST 2006

Arghhh the purist in my recoils at 'modernizing' an antique French timepiece <grin>

There would probably be some benefit to making the pendulum (or balance) consistently a bit slower than the quartz standard so that the pull is always in the same direction to avoid hunting (it's interesting that many biological clocks work this way, without diurnal cues, they run long (25 hr or so) so that the stabilizing influence is always in the same direction.

Cukoo clocks are terrible timekeepers, the pendulum is light (subject to air resistance), not thermo compensated, swings in a wide arc (circular error), have very sloppy mechanical tolerances and do not use a deadbeat escapement. A proper longcase clock is vastly better in every one of those areas.

>From: "Dr. David Kirkby" <david.kirkby at onetel.net>
>Date: Thu Jan 05 09:25:33 CST 2006
>To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
>Subject: Re: [time-nuts] Quartz assisted pendulum clock.

>Dennis O'Keefe wrote:
>> Earlier this week I made a claim that I am a Time Nut from way back. In 
>> further evidence of that, I report that I actually clipped and saved that 
>> article.
>> Reference: Scientific American, September 1974, pages 192 - 198, in a section 
>> called The Amateur Scientist.
>> The man made a quarts crystal oscillator that sent a pulse to an electromagnet 
>> that was placed near a permanent magnet mounted on the pendulum of a wall (not 
>> a grandfather) clock. The pendulum was set a bit slow for its 72 per minuet 
>> beat and the electronics gave it a push each cycle to make it swing at the 
>> correct rate.
>> He had faster and slower count settings to adjust its rate. The ultimate check 
>> was still listening to WWV while looking at the clock.
>If you have an electronic copy of that I'd like to see it. I found a 
>text-only version, but would like to see the original.
>I believe he used a TCXO. I have a small French clock that sits on a 
>mantelpiece, I'd like to do that too, but getting power to it is not too 
>easy. My wife is not keen on wires going to it.
>I did think about solar power, or powering it from the pendulum itself, 
>but neither look too practical in my particular circumstances.
>I did wonder if its possible to put the electromagnet under the clock, 
>rather than inside it, but that will probably put too much wear on the 
>You can probably cut down the power consumption by running the clock at 
>as accurate as possible (not slow) and using a bipolar pulse, rather 
>than a uni-polar one.
>Certainly an interesting idea.
>BTW, if you look at the sound produced by an old clock wth a microphone 
>and scope, it is far from regular. I suspect the pendulum is more so 
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