File:Detector magnetico Marconi 1902 - Museo scienza e tecnologia Milano.jpg
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Summary
DescriptionDetector magnetico Marconi 1902 - Museo scienza e tecnologia Milano.jpg |
Italiano: Detector magnetico Marconi utilizzato nella campagna sperimentale a bordo della Carlo Alberto nell'estate del 1902. Esposto al Museo nazionale della scienza e della tecnologia Leonardo da Vinci di Milano.
English: One of the earliest prototype magnetic detectors, built by inventor Guglielmo Marconi and used in his wireless experiments on board the ship Carlo Alberto in the summer of 1902. The magnetic detector was a primitive radio wave detector used in the first wireless telegraphy radio receivers from its invention in 1902 to about 1915, when it was replaced by vacuum tubes. An endless band of iron wires (apparently missing from this device) was rotated around the two pulleys. driven by a windup clockwork mechanism in the box. The wires passed through a coil attached to the antenna, in the magnetic field produced by the two horseshoe magnets (center). When a radio wave from the antenna passed through the coil, it's oscillating magnetic field overcame the hysteresis of the iron wires, magnetizing them. This produced a pulse of current in a second coil around the wires, attached to an earphone. The signals produced by the early spark gap transmitters consisted of pulses of damped radio waves, repeating at an audio rate, so in the earphone the received signal sounded like musical beeps. Text messages were transmitted in the sequence of beeps by Morse code, which the operator decoded. Exhibited at National Museum of Science and Technology Leonardo da Vinci in Milan, Italy. |
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institution QS:P195,Q947082 |
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Author | Alessandro Nassiri for Museo nazionale scienza e tecnologia L. da Vinci |
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4 December 2012
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Date/Time | Dimensions | User | Comment | |
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current | 13:17, 25 April 2016 | 1,980 × 1,320 (566 KB) | Marco Chemello (Museoscienza) | User created page with UploadWizard |
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Camera manufacturer | Canon |
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Camera model | Canon EOS 5D Mark II |
Copyright holder |
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Exposure time | 1/60 sec (0.016666666666667) |
F Number | f/16 |
ISO speed rating | 100 |
Date and time of data generation | 12:37, 4 December 2012 |
Lens focal length | 73 mm |
Horizontal resolution | 180 dpi |
Vertical resolution | 180 dpi |
Software used | Adobe Photoshop Lightroom 5.6 (Windows) |
File change date and time | 12:38, 31 March 2016 |
Exposure Program | Manual |
Exif version | 2.3 |
Date and time of digitizing | 12:37, 4 December 2012 |
APEX shutter speed | 5.906891 |
APEX aperture | 8 |
APEX exposure bias | 0 |
Maximum land aperture | 4 APEX (f/4) |
Subject distance | 1.68 meters |
Metering mode | Spot |
Flash | Flash fired, compulsory flash firing |
DateTimeOriginal subseconds | 48 |
DateTimeDigitized subseconds | 48 |
Color space | sRGB |
Focal plane X resolution | 3,849.2117888965 |
Focal plane Y resolution | 3,908.1419624217 |
Focal plane resolution unit | inches |
Custom image processing | Normal process |
Exposure mode | Manual exposure |
White balance | Auto white balance |
Scene capture type | Standard |
Serial number of camera | 2931503347 |
Lens used | EF24-105mm f/4L IS USM |
Date metadata was last modified | 14:38, 31 March 2016 |
Label | Blu |
Source | Museo Nazionale della Scienza e della Tecnologia Leonardo da Vinci |
Unique ID of original document | 642912E3836D03979CDFD8E4A5B4D76A |
Copyright status | Copyrighted |
Online copyright statement | http://creativecommons.org/licenses/by-sa/4.0/ |
Usage terms |
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IIM version | 4 |