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Early steam-powered vacuum cleaners were mounted in a heavy carriage equipped with a long hose so they could be moved from one location to another, providing a specialized cleaning service by appointment. Stationary-powered vacuum cleaners were built-in and centralized, due to the large and heavy machinery needed to produce the required airflow.
Discharge tubes with hot cathodes have an envelope filled with low-pressure gas and containing two electrodes. Hot cathode devices include common vacuum tubes, fluorescent lamps, high-pressure discharge lamps and vacuum fluorescent displays. The surface of cold cathodes can emit secondary electrons at a ratio greater than unity (breakdown). An ...
Materials for use in vacuum are materials that show very low rates of outgassing in vacuum and, where applicable, are tolerant to bake-out temperatures. The requirements grow increasingly stringent with the desired degree of vacuum to be achieved in the vacuum chamber. The materials can produce gas by several mechanisms.
The General Electric automatic toothbrush was introduced in the early 1960s; [6] it was cordless, with rechargeable NiCad batteries and although portable, was rather bulky, about the size of a two-D-cell flashlight handle. [7] NiCad batteries of this period suffered from the memory effect. The GE automatic toothbrush came with a charging stand ...
Eveready 761 "C" battery with 4.5-volt, 3-volt, 1.5-volt tap screw terminals. The "C" battery is used to provide bias to the control grid. Until the early 1930s this was common practice in valve (tube) radio sets but was largely superseded by grid leak resistors or voltage divider biasing. Because the tube grids draw no current, the "C" battery ...
Later thermionic vacuum tubes, mostly miniature style, some with top cap connections for higher voltages. A vacuum tube, electron tube, [1] [2] [3] thermionic valve (British usage), or tube (North America) [4] is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied.
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