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3D3DRubidium time standard.
I feel a bit guilty about this sample. It started as a perfectly good, said to be entirely functional, Efratom FRS 10MHz time standard, which I ruthlessly tore apart to get to the glass ampule you see here, which contains a tiny amount of rubidium. It will never tell time again. In operation heating coils would have raised the temperature of the ampule enough to vaporize the rubidium. Radio frequency coils then excite the rubidium atoms and measure the frequency of their electronic transitions, which are very stable. (Cesium atomic clocks work on the same principle and are even more accurate, but for some reason rubidium ones are cheaper.)
I've left as much circuitry as I could on the ampule. This module was completely enclosed in circuit boards on four sides, and the whole assembly was built into a metal can.
Source: eBay seller nhbbobb1985
Contributor: Theodore Gray
Acquired: 19 November, 2008
Text Updated: 29 January, 2009
Price: $38
Size: 2"
Purity: 99.9%