Jump to ContentJump to Main Navigation
Accurate Clock Pendulums$
Users without a subscription are not able to see the full content.

Robert J. Matthys

Print publication date: 2004

Print ISBN-13: 9780198529712

Published to Oxford Scholarship Online: January 2010

DOI: 10.1093/acprof:oso/9780198529712.001.0001

Show Summary Details
Page of

PRINTED FROM OXFORD SCHOLARSHIP ONLINE (www.oxfordscholarship.com). (c) Copyright Oxford University Press, 2019. All Rights Reserved. Under the terms of the licence agreement, an individual user may print out a PDF of a single chapter of a monograph in OSO for personal use (for details see www.oxfordscholarship.com/page/privacy-policy).date: 23 July 2019

Electronic correction for air pressure variations

Electronic correction for air pressure variations

Chapter:
(p.255) Chapter 36 Electronic correction for air pressure variations
Source:
Accurate Clock Pendulums
Author(s):

Robert James Matthys

Publisher:
Oxford University Press
DOI:10.1093/acprof:oso/9780198529712.003.0036

At atmospheric pressure, a pendulum is slightly buoyant to a ‘sea’ of air. This buoyancy causes the pendulum's timing to be a little sensitive to the air's density, and consequently to its pressure. Timing error can be corrected mechanically by putting a small bellows-supported weight on the pendulum. As the air pressure increases, the bellows shrinks and lowers the weight resting on top of it, speeding up the pendulum to compensate for its natural slowdown with increasing pressure. This assumes that the bellows' weight is located in the pendulum's upper half. If located in the lower half, the bellows-supported weight must hang below the bellows instead of sitting on top of it. The effect of the air pressure variations can also be corrected for electronically, using a silicon-based pressure sensor, some electronic circuitry, and an electromagnetic (coil and magnet) pendulum drive. This chapter describes an electronic circuit that corrects for a pendulum's air pressure variations.

Keywords:   air pressure, pendulum, bellows, pressure sensor, electronic circuit, electromagnetic drive

Oxford Scholarship Online requires a subscription or purchase to access the full text of books within the service. Public users can however freely search the site and view the abstracts and keywords for each book and chapter.

Please, subscribe or login to access full text content.

If you think you should have access to this title, please contact your librarian.

To troubleshoot, please check our FAQs , and if you can't find the answer there, please contact us .