- Title Pages
- Preface
- Introduction
- Chapter 1 Better accuracy from simple pendulums
- Chapter 2 A short history of temperature compensation
- Chapter 3 Scaling the size of a pendulum
- Chapter 4 Finding a pendulum’s axis of rotation
- Chapter 5 Does a pendulum’s axis of rotation shift with amplitude?
- Chapter 6 Some practical properties of quartz
- Chapter 7 Putting Q in perspective
- Chapter 8 The Allan variance and the rms time error
- Chapter 9 Transient temperature effects in a pendulum
- Chapter 10 Transient response of a pendulum to temperature change
- Chapter 11 Dimensional stability of pendulum materials
- Chapter 12 Variations on a Riefler bob shape
- Chapter 13 Bob shape
- Chapter 14 Rate adjustment mechanisms
- Chapter 15 Spring suspensions for accurate pendulums
- Chapter 16 James’ suspension spring equations
- Chapter 17 Barometric compensation with a crossed spring suspension?
- Chapter 18 Solid one-piece suspension springs
- Chapter 19 Stable connections to a pendulum’s suspension spring
- Chapter 20 Stability of suspension spring materials
- Chapter 21 Pendulum rod materials
- Chapter 22 The heat treatment of invar
- Chapter 23 The instability of invar
- Chapter 24 Position sensitivity along the pendulum rod
- Chapter 25 Fasteners for quartz pendulum rods
- Chapter 26 Effect of the pendulum rod on Q
- Chapter 27 Correcting the pendulum’s air pressure error
- Chapter 28 Pendulum air movement: A failed experiment
- Chapter 29 Pendulum air movement: A second try
- Chapter 30 Time error due to air pressure variations
- Chapter 31 Effect of the clock case walls on a pendulum
- Chapter 32 An electronically driven pendulum
- Chapter 33 Sinusoidal drive of a pendulum
- Chapter 34 Photoelectronics for pendulums
- Chapter 35 Check your clock against WWV
- Chapter 36 Electronic correction for air pressure variations
- Conversion Table
- Index
Photoelectronics for pendulums
Photoelectronics for pendulums
- Chapter:
- (p.241) Chapter 34 Photoelectronics for pendulums
- Source:
- Accurate Clock Pendulums
- Author(s):
Robert James Matthys
- Publisher:
- Oxford University Press
Photoelectronics make good sensors for pendulum clocks, because they add no power losses to the pendulum. A swinging pendulum interrupts a light beam, and a light detector provides an electrical signal to compare to a time standard or to incrementally drive the second hand on a clock face. Most photoelectronic circuitry is aimed at very simple applications, such as counting slow-moving cans or boxes on a production line, or detecting the passage of a slow-moving pendulum. For the pendulum application, where the light source and light detector are about a half-inch or so apart, the most suitable light source is an infrared light emitting diode. There are four basic things that can be done to improve the dimensional and time resolutions of a pendulum: narrow the light beam down to just a slit width, use a voltage comparator on the light detector's output signal, better stray light reduction, and use a faster light detector.
Keywords: photoelectronics, pendulum clocks, pendulum, light emitting diode, light source, time resolution, light beam, voltage comparator, light detector
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- Title Pages
- Preface
- Introduction
- Chapter 1 Better accuracy from simple pendulums
- Chapter 2 A short history of temperature compensation
- Chapter 3 Scaling the size of a pendulum
- Chapter 4 Finding a pendulum’s axis of rotation
- Chapter 5 Does a pendulum’s axis of rotation shift with amplitude?
- Chapter 6 Some practical properties of quartz
- Chapter 7 Putting Q in perspective
- Chapter 8 The Allan variance and the rms time error
- Chapter 9 Transient temperature effects in a pendulum
- Chapter 10 Transient response of a pendulum to temperature change
- Chapter 11 Dimensional stability of pendulum materials
- Chapter 12 Variations on a Riefler bob shape
- Chapter 13 Bob shape
- Chapter 14 Rate adjustment mechanisms
- Chapter 15 Spring suspensions for accurate pendulums
- Chapter 16 James’ suspension spring equations
- Chapter 17 Barometric compensation with a crossed spring suspension?
- Chapter 18 Solid one-piece suspension springs
- Chapter 19 Stable connections to a pendulum’s suspension spring
- Chapter 20 Stability of suspension spring materials
- Chapter 21 Pendulum rod materials
- Chapter 22 The heat treatment of invar
- Chapter 23 The instability of invar
- Chapter 24 Position sensitivity along the pendulum rod
- Chapter 25 Fasteners for quartz pendulum rods
- Chapter 26 Effect of the pendulum rod on Q
- Chapter 27 Correcting the pendulum’s air pressure error
- Chapter 28 Pendulum air movement: A failed experiment
- Chapter 29 Pendulum air movement: A second try
- Chapter 30 Time error due to air pressure variations
- Chapter 31 Effect of the clock case walls on a pendulum
- Chapter 32 An electronically driven pendulum
- Chapter 33 Sinusoidal drive of a pendulum
- Chapter 34 Photoelectronics for pendulums
- Chapter 35 Check your clock against WWV
- Chapter 36 Electronic correction for air pressure variations
- Conversion Table
- Index