Accurate Clock Pendulums

Contents......Page 6
Preface......Page 8
Introduction......Page 10
Part I: General......Page 12
1. Better accuracy from simple pendulums......Page 14
2. A short history of temperature compensation......Page 18
3. Scaling the size of a pendulum......Page 24
4. Finding a pendulum’s axis of rotation......Page 30
5. Does a pendulum’s axis of rotation shift with amplitude?......Page 32
6. Some practical properties of quartz......Page 34
7. Putting Q in perspective......Page 38
8. The Allan variance and the rms time error......Page 48
9. Transient temperature effects in a pendulum......Page 54
10. Transient response of a pendulum to temperature change......Page 58
11. Dimensional stability of pendulum materials......Page 68
12. Variations on a Riefler bob shape......Page 90
13. Bob shape......Page 98
14. Rate adjustment mechanisms......Page 102
Part II: Suspension spring......Page 106
15. Spring suspensions for accurate pendulums......Page 108
16. James’ suspension spring equations......Page 132
17. Barometric compensation with a crossed spring suspension?......Page 138
18. Solid one-piece suspension springs......Page 142
19. Stable connections to a pendulum’s suspension spring......Page 150
20. Stability of suspension spring materials......Page 154
Part III: Pendulum rod......Page 164
21. Pendulum rod materials......Page 166
22. The heat treatment of invar......Page 170
23. The instability of invar......Page 174
24. Position sensitivity along the pendulum rod......Page 178
25. Fasteners for quartz pendulum rods......Page 182
26. Effect of the pendulum rod on Q......Page 190
Part IV: Air and clock case effects......Page 194
27. Correcting the pendulum’s air pressure error......Page 196
28. Pendulum air movement: A failed experiment......Page 202
29. Pendulum air movement: A second try......Page 206
30. Time error due to air pressure variations......Page 216
31. Effect of the clock case walls on a pendulum......Page 222
Part V: Electronics......Page 232
32. An electronically driven pendulum......Page 234
33. Sinusoidal drive of a pendulum......Page 238
34. Photoelectronics for pendulums......Page 252
35. Check your clock against WWV......Page 260
36. Electronic correction for air pressure variations......Page 266
Conversion Table......Page 272
W......Page 274