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Telechron synchronous electric clock manufactured around 1940. By 1940, the synchronous clock became the most common type of clock in the United States. 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 electric clock market grew rapidly in the 1930s, and Telechron's patented power interruption indicator gave his clocks an advantage over competing synchronous clocks, but by the 1950s battery-operated clocks that weren't dependent on the power grid took market share, and in the 1960s the quartz clock replaced synchronous clocks.
The Hammond clock model "Como" The Hammond Clock Company was founded in 1928 to produce and market clocks that were equipped with Hammond's new motor. The Hammond clock factory manufactured more than 100 different clock models, some simple and cheap, others made from expensive materials such as marble and onyx. [4]
The Standard Electric Time Company was a Springfield, Massachusetts company founded in 1884, and was a manufacturer of synchronized clock systems and fire alarm systems. They were the oldest manufacturer of electric clocks in the United States. The company was acquired by Johnson Controls in 1970 and then Faraday in 1978.
Synchronous electric clocks do not have an internal oscillator, but count cycles of the 50 or 60 Hz oscillation of the AC power line, which is synchronized by the utility to a precision oscillator. The counting may be done electronically, usually in clocks with digital displays, or, in analog clocks, the AC may drive a synchronous motor which ...
This page was last edited on 11 April 2013, at 17:24 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may ...
The next 3 decades saw the development of quartz clocks as precision time standards in laboratory settings; the bulky delicate counting electronics, built with vacuum tubes, limited their use elsewhere. In 1932 a quartz clock was able to measure tiny variations in the rotation rate of the Earth over periods as short as a few weeks. [39]
Schematic of a split-flap display in a digital clock display. An electric motor (often synchronous, if directly connected to the AC line) turns two sets of wheels continuously via a reduction gear train: the faster at a rate of 1 revolution per hour, the slower at a rate of 1 revolution per 24 hours. The wheels move continuously, not in steps.
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