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Showing posts from January, 2019

Jefferson "Golden Hour" Electric Clock

Description Jefferson Electric "Golden Hour" electric clock, USA. c1950. The first and best of a series of mystery clocks. The clock is transparent, with no obviuos way for the hands to turn. The crystal itself rotated driving the minute hand and a small gearbox at the rear drives the hour hand. A sycronous electric clock, so very accurate. 60 Hz so I need an inverter to generate 110 V 60 Hz. Diecast metal with gold plating. Fairly expensive in its day, about US$22. Aimed at upper-income people as a special gift for birthdays and the like. Significance Smart. A mystery clock, very well done. In the spirit of complex clocks but seeminly very simple. Made for 40 years from late 1949, selling over 2 million. http://www.roger-russell.com/jeffers/jeffers.htm  Very detailed.

National Transistor Clock Japan Battery Pendulum

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Draft- Awaiting more information?? Description A battery-powered, electro-mechanical pendulum clock from National Japan, the National Transistor Clock. c1970. So cute. So rare too! Only one on eBay worldwide and in Australia too. Significance A Japanese battery pendulum clock in a glass case c1970, similar to the earlier Bulle clocks, 1920 to 1950s. Similarly, the battery-powered pendulm movement avoids the need to wind a spring. At a guess, the battery lasts about a year. Made in the period just after transistors became avaiable but just before quartz electronic clocks dominated, so numbers are low. Transistor switching is used for power to the electromagnetic coils that the pendulum swings between. The pendulum is a permanent magnet(??). In the Bulle clocks, the permanent magnet is fixed and the electromagnet is on the pendulum, with mechanical switching. Transistor switching is mechanically simpler but the pendulum has the weight of a iron permanent magnet. Howard Milla...

Smiths Bakelite Electric Mantle Clock: 50 Hz England

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An inexpensive electric syncronous clock made in England for the 240V 50 Hz system, subsequently used in Australia. c1930s through1950s. An electric clock rotates in accordance to its electricity supply frequency that is mainted for high longterm accuracy. Significance Hammond is credited with the invention of the inexpensive electric syncronous clock in the late 1920s and encouraged grid operators to closely regulate frequency using master clocks to allow their use. Electric clocks were more accurate and cheaper than mechanical clocks and did not need winding, contributing to the demise of mechanical clocks. An electric clock loses its time if the supply is cut temporarily. Some electric clocks need to be re-started, so the user is alerted to the time error, but others automatically restart and show the incorrect time. The frequency of alternating current (AC) electricity grids is kept at a very precise frequency, in part for time keeping. Initially, very accurate master cloc...

Shipwrecked! Hamilton Model 22 marine chronometer

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Significance The USA was caught unaware by the bombing of Pearl Harbour in 1942 and entered WWII needing a quick supply of marine chronometers. Hamilton won the contract and produced about 11,000 technically advanced marine chronometers. The model 22 is a major upgrade in the largely static design of marine chronometers and is more accurate. The Hamilton model 22 is made as both a gimbaled chronometer like earlier ones and as a large pocket watch to be used as a deck watch. The deck watch was adjusted to match the time of the main ship's chronometer then taken on deck with a sextant to take navigation observations. Many chronometers went down with the ship! This is one and just the movement. It has severe saltwater corrosion of the steel parts, however, the working of the chronometer can be seen. Yes, it is a bit of a laugh but serviceable ones are way beyond my budget. Besides, shipwrecked ones are probably rarer than serviceable ones.  Another one but...

Bulle battery electro-mechanical pendulum clock

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Significance A pendulum clock that doesn't need winding, just its battery replaced each year. Reasonably accurate because of a pendulum when adjusted carefully. Uses the then-new electricity in the 1920s. Super cute too! Shows the workings of the mechanism. Description Electro-mechanical. Battery powered, 1.5 V cell. Electromagnetic pulse to keep pendulum working. The coil is on the pendulum which moves in an arc over a rod that is permanently magnetised. The pulse is triggered so that opposite magnetic poles attract and like repel. The impulse is probably more gentle than that from a spring-escapement mechanism. Glass case pendulum desirable to see mechanism working. Are expensive when restored. Made in France 1920s - 1950s, approx 300,000 made. Bought on eBay after another sniper shootout early in the morning, the item from Spain.   My Belle clock, glass on all sides to show movement. Restored when bought. The dial is in very good ...