1891 – History of cinema: The first public display of Thomas Edison’s prototype kinetoscope.
The Kinetoscope is an early motion picture exhibition device. The Kinetoscope was designed for films to be viewed by one individual at a time through a peephole viewer window at the top of the device. The Kinetoscope was not a movie projector but introduced the basic approach that would become the standard for all cinematic projection before the advent of video, by creating the illusion of movement by conveying a strip of perforated film bearing sequential images over a light source with a high-speed shutter. First described in conceptual terms by U.S. inventor Thomas Edison in 1888, it was largely developed by his employee William Kennedy Laurie Dickson between 1889 and 1892. Dickson and his team at the Edison lab also devised the Kinetograph, an innovative motion picture camera with rapid intermittent, or stop-and-go, film movement, to photograph movies for in-house experiments and, eventually, commercial Kinetoscope presentations.
1913 – William Redington Hewlett, American engineer, co-founded Hewlett-Packard is born.
Today would be the 99th birthday of American electrical engineer and Hewlett-Packard co-founder William (Bill) Hewlett (right, with Dave Packard left, above).
In 1939, Hewlett completed his EE masters thesis at Stanford. His thesis project was a variation of the Wien bridge oscillator, in which he used the negative resistance of an incandescent lamp to act as a parasitic impedance in the feedback loop. This ensured that the oscillator operated just at unity gain, and thus produced steady, low-distortion output.
This was a really clever and elegant hack — many oscillators of the time did not produce steady oscillations, but instead fed a pulse stream (sometimes just a rectified mains signal) to an RLC tank circuit with a large Q — so the output was a series of decaying oscillation patterns with modulation at this pulse frequency. Oscillators which did produce steady output were large and expensive. Hewlett replaced the complex control systems of these with a simple light bulb.
HP’s first product, the HP200A bench oscillator (on the left, above), was based on Hewlett’s thesis design, optimized for manufacturing in the now famous garage in Silicon Valley.
1932 – Amelia Earhart takes off from Newfoundland to begin the world’s first solo nonstop flight across the Atlantic Ocean by a female pilot, landing in Ireland the next day.
At the age of 34, on the morning of May 20, 1932, Earhart set off from Harbour Grace, Newfoundland with the latest copy of a local newspaper (the dated copy was intended to confirm the date of the flight). She intended to fly to Paris in her single engine Lockheed Vega 5B to emulate Charles Lindbergh’s solo flight. Her technical advisor for the flight was famed Norwegian American aviator Bernt Balchen who helped prepare her aircraft. He also played the role of “decoy” for the press as he was ostensibly preparing Earhart’s Vega for his own Arctic flight. After a flight lasting 14 hours, 56 minutes during which she contended with strong northerly winds, icy conditions and mechanical problems, Earhart landed in a pasture at Culmore, north of Derry, Northern Ireland. The landing was witnessed by Cecil King and T. Sawyer. When a farm hand asked, “Have you flown far?” Earhart replied, “From America.” The site now is the home of a small museum, the Amelia Earhart Centre.
What is a Force Sensitive Resistor?
FSR’s (Force Sensitive Resistors) are basically a resistor that changes its resistive value (in ohms Ω) depending on how much its pressed. These sensors are fairly low cost, and easy to use but they’re rarely accurate. They also vary some from sensor to sensor perhaps 10%. So basically when you use FSR’s you should only expect to get ranges of response. While FSRs can detect weight, they’re a bad choice for detecting exactly how many pounds of weight are on them…
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