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HP-19C calculator HP-29C with AC-powered battery charger. The HP-19C and HP-29C were scientific/engineering pocket calculators made by Hewlett-Packard between 1977 and 1979. They were the most advanced and last models of the "20" family (compare HP-25) and included Continuous Memory (battery-backed CMOS memory) as a standard feature.
Van de Graaff generator diagram. A simple Van de Graaff generator consists of a belt of rubber (or a similar flexible dielectric material) moving over two rollers of differing material, one of which is surrounded by a hollow metal sphere. A comb-shaped metal electrode with sharp points (2 and 7 in the diagram), is positioned near each roller ...
As an example, a 250 kVA motor–generator operating at 300 ampere of full load current will require 1550 ampere of in-rush current during a re-closure after 5 seconds. This example used a fixed mounted flywheel sized to result in a 1 ⁄ 2 Hz per second slew rate. The motor–generator was a vertical type two-bearing machine with oil-bath ...
For forty years the arithmometer was the only type of mechanical calculator available for sale until the industrial production of the more successful Odhner Arithmometer in 1890. [ 8 ] The comptometer , introduced in 1887, was the first machine to use a keyboard that consisted of columns of nine keys (from 1 to 9) for each digit.
Four wool spinning machines driven by belts from an overhead lineshaft (Leipzig, Germany, circa 1925) The belt drives of the Mueller Mill, model and reality, in motionA line shaft is a power-driven rotating shaft for power transmission that was used extensively from the Industrial Revolution until the early 20th century.
Automotive alternators are usually belt-driven at 2–3 times crankshaft speed, speeds that could cause a commutator to fly apart in a generator. The alternator runs at various RPM (which varies the frequency) since it is driven by the engine. This is not a problem because the alternating current is rectified to direct current.
Main Wikipedia article: Electrical generator Description: Dynamos are no longer used for power generation due to the size and complexity of the commutator needed for high power applications. This large belt-driven high-current dynamo produced 310 amperes at 7 volts, or 2,170 watts, when spinning at 1400 RPM.
The open belt drive has parallel shafts rotating in the same direction, whereas the cross-belt drive also bears parallel shafts but rotate in opposite direction. The former is far more common, and the latter not appropriate for timing and standard V-belts unless there is a twist between each pulley so that the pulleys only contact the same belt ...