By Robert James Matthys
The Shortt clock, made within the 1920's is the main recognized exact clock pendulum ever identified, having an accuracy of 1 moment in line with yr while stored at approximately consistent temperature. just about all of a pendulum clock's accuracy is living in its pendulum. If the pendulum is actual, the clock should be exact. during this e-book, the writer describes many clinical features of pendulum layout and operation purely with experimental info, and little arithmetic. it's been written, taking a look at the entire varied components and features of the pendulum in nice element, bankruptcy via bankruptcy, reflecting the measure of cognizance useful for creating a pendulum run properly. the themes lined contain the dimensional balance of alternative pendulum fabrics, reliable and negative suspension spring designs, the layout of mechanical joints and clamps, impact of quartz on accuracy, temperature reimbursement, air drag of other bob shapes and making s sinusoidal electromagnetic force. One complete bankruptcy is dedicated to basic methods of enhancing the accuracy of normal inexpensive pendulum clocks, that have a special building to the dearer designs of considerably well-made ones. This ebook will turn out helpful to a person who desires to know the way to make a extra actual pendulum or pendulum clock.
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Extra info for Accurate Clock Pendulums
Standard terminology for fundamental frequency and time metrology,” 42nd Annu. Freq. Control Symp. (1988), pp. 419–25. Also in [6, TN–139]. P. Woodward. My own right time, Oxford University Press, 1995, pp. 124–5. D. Allan and H. Hellwig. “Time deviation and time prediction error for clock specification, characterization, and application,” Proc. Position Locat. Navig. Symp. (PLANS), 1978, p. 29. D. Allan. “Time and frequency (time-domain) characterization, estimation, and prediction of precision clocks and oscillators,” IEEE Trans.
Conclusions I think the traditional graphs of a clock’s actual time error and leveled time error vs time are still the best way to show a clock’s time performance. A clock’s Allan variance is essentially just a number on a global performance scale containing all types of oscillators, and provides no really useful information to the pendulum clockmaker. However, the variance can be used to calculate the rms time error, which is useful to him. Unfortunately, both the variance and the rms time error have inherently short time scales, amounting at most to onefifth of the length of the actual and leveled time error curves.
3 orders of magnitude, or 2000 to 1. At a fixed Q level, the accuracy width of the broad line is about 3 orders of magnitude, or 1000 to 1. Even with a fixed Q, a clock accuracy variation of 1000 to 1 certainly leaves plenty of room for an individual clockmaker to express his own ideas and taste in clock design. Discussion I was not much impressed with the first argument for Q, as all of the components in its error equation were previously known. That is, to make an accurate pendulum clock, impulse it at the center of swing, as constantly and repeatedly as possible; and make the pendulum as efficient as possible, so that the impulse is as small as possible and disturbs the pendulum as little as possible.
Accurate Clock Pendulums by Robert James Matthys