Electric clock
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An electric clock is a clock that is powered by electricity, as opposed to a mechanical clock which is powered by a hanging weight or a mainspring. The term is often applied to the electrically powered mechanical clocks that were used before quartz clocks were introduced in the 1980s. The first experimental electric clocks were constructed around the 1840s, but they were not widely manufactured until mains electric power became available in the 1890s. In the 1930s, the synchronous electric clock replaced mechanical clocks as the most widely used type of clock.
Types
Electric clocks can operate by several different types of mechanism:
- Electromechanical clocks have a traditional mechanical movement, which keeps time with an oscillating pendulum or balance wheel powered through a gear train by a mainspring, but use electricity to rewind the mainspring with an electric motor or electromagnet. This mechanism is found mostly in antique clocks.
- Electric remontoire clocks have gear trains turned by a small spring or weighted lever, called a remontoire, which was wound up more frequently by an electric motor or electromagnet. This mechanism was more accurate than a mainspring, because the frequent winding averaged out variations in the clock's rate caused by the varying force of the spring as it unwound. It was used in precision pendulum clocks, and in automotive clocks until the 1970s.
- Electromagnetic clocks keep time with a pendulum or balance wheel, but the pulses to keep it going are not provided by a mechanical movement and magnetic force from an electromagnet (solenoid). This was the mechanism used in the first electric clocks, and is found in antique electric pendulum clocks. It is also found in a few modern decorative mantel and desk clocks.
- Synchronous clocks rely on the 50 or 60 Hz power cuts; over months they are more accurate than a typical quartz clock. This was the most common type of clock from the 1930s but has now been mostly replaced by quartz clocks.
- Tuning Fork clocks keep time by counting the oscillations of a calibrated tuning fork with a specific frequency. These were only made in battery-powered form. Battery-powered clocks have been made using the schemes above with the obvious exception of a synchronous movement. All battery-powered clocks have been largely replaced by the lower cost quartz movement.
- quartz crystal. They use modern low-voltage DC-powered circuitry, which may be supplied by a battery or derived from mains electricity. They are the most common type of clock today. Quartz clocks and watches as supplied by the manufacturer typically keep time with an error of a few seconds per week, although sometimes more.[1] Inexpensive quartz movements are often specified to keep time within 30 seconds per month (1 second per day, 6 minutes per year).[2]Lower error can be achieved by individual calibration if adjustment is possible, subject to the stability of the oscillator, particularly with change in temperature. Higher accuracy is possible at higher cost.
- clock radios.
History
In 1814,
In 1815,
In 1840, Alexander Bain, a Scottish clock and instrument maker was the first to invent and patent a clock powered by electric current. His original electric clock patent is dated October 10, 1840. On January 11, 1841, Alexander Bain along with John Barwise, a chronometer maker, took out another important patent describing a clock in which an electromagnetic pendulum and an electric current is employed to keep the clock going instead of springs or weights. Later patents expanded on his original ideas.
Numerous people were intent on inventing the electric clock with electromechanical and electromagnetic designs around the year 1840, such as Wheatstone, Steinheil, Hipp, Breguet, and Garnier, both in Europe and America.
Matthäus Hipp , clockmaker born in Germany, is credited with establishing the production series, mass marketable electric clock. Hipp opened a workshop in Reutlingen, where he developed an electric clock to have the Hipp-Toggle, presented in Berlin at an exhibition in 1843. The Hipp-Toggle is a device attached to a pendulum or balance wheel that electro-mechanically allows occasional impulse or drive to the pendulum or wheel as its amplitude of swing drops below a certain level, and is so efficient that it was subsequently used in electric clocks for over a hundred years. Hipp also invented a small motor and built the chronoscope and the registering chronograph for time measurement.
The first electric clocks had prominent pendulums because this was a familiar shape and design. Smaller clocks and watches with a spiral-balance are made on the same principles as pendulum clocks.
In 1918, Henry Ellis Warren invented the first synchronous electric clock in Ashland, MA, which kept time from the oscillations of the power grid.[7][8] In 1931, the Synclock was the first commercial synchronous electric clock sold in the UK.[8]
Electromechanical clock
A clock that employs electricity in some form to power a conventional clock mechanism is an electromechanical clock. Any spring or weight driven clock that uses electricity (either AC or DC) to rewind the spring or raise the weight of a mechanical clock then is an electromechanical clock. In electromechanical clocks the electricity serves no time keeping function. The timekeeping function is regulated by the pendulum. Near the end of the nineteenth century, the availability of the dry cell battery made it practical to use electric power in clocks. The use of electricity then led to many variations of clock and motor designs. Electromechanical clocks were made as individual timepieces but most commonly were used as integral parts of synchronized time installations. Experience in telegraphy led to connecting remote clocks (slave clocks) via wires to a controlling (master clock) clock. The goal was to create a clock system where each clock displayed exactly the same time. The master and the slaves are electromechanical clocks. The
Electromagnetic clock
The configuration of this device is comparatively very simple and reliable. The electric current powers either a
The electromechanical oscillator component has an attached
Synchronous electric clock
A synchronous electric clock does not contain a timekeeping oscillator such as a pendulum or balance wheel, but instead counts the oscillations of the AC
One of the gears turning the clock's hands has a shaft with a sliding friction fitting, so the clock's hands can be turned manually by a knob on the back or on the bottom, to set the clock.
Synchronous motor clocks are rugged because they do not have a delicate pendulum or balance wheel. However, a temporary power outage will stop the clock, which will show the wrong time when power is restored. Some synchronous clocks (e.g. Telechron) have an indicator which shows if it has stopped and restarted.
Number of poles
Some electric clocks have a simple two-pole synchronous motor which runs at one revolution per cycle of power, i.e., 3600 RPM at 60 Hz and 3000 RPM at 50 Hz.[10] However most electric clocks have rotors with more magnetic poles (teeth), consequently rotating at a smaller submultiple of line frequency. This allows the gear train which turns the hands to be built with fewer gears, saving money.[11]
Accuracy
The accuracy of synchronous clocks depends on how close
In 2011, the
Spin-start clocks
The earliest synchronous clocks from the 1930s were not self-starting, and had to be started by spinning a starter knob on the back.[9] A flaw in the design of these spin-start clocks was that the motor could be started in either direction, so if the starter knob was spun the wrong way the clock would run backwards, the hands turning counterclockwise. Later manual-start clocks had ratchets or other linkages which prevented backwards starting. The invention of the shaded-pole motor allowed self-starting clocks to be made, but since the clock would then restart after a power outage, the clock would give incorrect time instead of being stopped at the time of power interruption.
See also
- Master clock
- Shortt-Synchronome clock
- Automatic watch
Notes
- ^ Elliott, Rod. "Build a Synchronous Clock". Elliott Sound. Archived from the original on 2018-07-11. Retrieved 2016-12-13.
- ^ Brimarc, typical quartz clock movement specified accurate to within ±30 seconds/month Archived 2015-07-04 at the Wayback Machine
- ^ Aked, C.K. (1973). "The First Electric Clock". Antiquarian Horology.
- ISBN 978-1-78326-917-4.
- ^ Ronalds, B.F. (Jun 2015). "Remembering the First Battery-Operated Clock". Antiquarian Horology. Retrieved 8 Apr 2016.
- ^ Perpetual Electromotive
- ^ U.S. patent #1283434 Warren, Henry E. Timing device, filed February 26, 1917, issued October 29, 1918, on Google Patents
- ^ a b "Famous Names in Electrical Horology". Electrical Horology Group. Antiquarian Horological Society, London, UK. 2011. Archived from the original on 2012-05-07. Retrieved 2011-12-16.
- ^ a b c Wise, S. J. (1952). Electric Clocks, 2nd Ed (PDF). London: Heywood & Co. pp. 95–100.[permanent dead link]
- ^ Wise (1952) Electric Clocks[permanent dead link], p.101–104
- ^ The speed of a synchronous motor v in revolutions per minute (RPM) is related to the number of poles by:
- ^ a b c d NIST Paper
- ^ "Frequency response - National Grid". www2.nationalgrid.com. Archived from the original on 2017-11-03. Retrieved 2016-06-03.
- ^ "NERC". www.nerc.com.
- ^ "Federal Energy Regulatory Commission". www.ferc.gov.
- ^ http://www.gps.gov/cgsic/meetings/2011/matsakis.pdf [bare URL PDF]
- ^ "Appliance disruptions feared in power grid test". CBS News. 27 June 2011.
- ^ "North American Energy Standards Board". www.naesb.org.
- ^ "NAESB Wholesale Electric Quadrant (WEQ) Update" (PDF). Archived from the original (PDF) on 2022-12-06. Retrieved 2022-01-07.
References
- Viradez, Michel. History of Electric Clocks
- Katz, Eugenii. Alexander Bain Biography
- Perpetual Electromotive of Giuseppe Zamboni
- Chirkin, K. Electromechanical clocks. Radio, 7 (1968): p. 43.