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Spark-gap transmitter
Videos
A spark-gap transmitter is an obsolete type of radio transmitter which generates radio waves by means of an electric spark. Spark-gap transmitters were the first type of radio transmitter, and were th
Low-power inductively coupled spark-gap transmitter on display in Electric Museum, Frastanz, Austria. The spark gap is inside the box with the transpa
Low-power inductively coupled spark-gap transmitter on display in Electric Museum, Frastanz, Austria. The spark gap is inside the box with the transparent cover at top center.
Demonstration of the restored 1907 Massie Wireless Station spark gap transmitter Audio of Massie spark gap transmission Morse code of "CQ DE PJ"
Demonstration of the restored 1907 Massie Wireless Station spark gap transmitter Audio of Massie spark gap transmission Morse code of "CQ DE PJ"
Hertzian spark oscillator, 1902. Visible are antenna consisting of 2 wires ending in metal plates (E), spark gap (D), induction coil (A), auto battery
Hertzian spark oscillator, 1902. Visible are antenna consisting of 2 wires ending in metal plates (E), spark gap (D), induction coil (A), auto battery (B), and telegraph key (C).
Jagadish Chandra Bose in 1894 was the first person to produce millimeter waves; his spark oscillator (in box, right) generated 60 GHz (5 mm) waves usi
Jagadish Chandra Bose in 1894 was the first person to produce millimeter waves; his spark oscillator (in box, right) generated 60 GHz (5 mm) waves using 3 mm metal ball resonators.
Coherer
Videos
The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the 20th century. Its use in radio was based on the 1
Marconi's 1896 coherer receiver, at the Oxford Museum of the History of Science, UK. The coherer is on right, with the decoherer mechanism behind it. The relay is in the cylindrical metal container (center) to shield the coherer from the RF noise from its contacts.
Marconi's 1896 coherer receiver, at the Oxford Museum of the History of Science, UK. The coherer is on right, with the decoherer mechanism behind it.
The circuit of a coherer receiver, that recorded the received code on a Morse paper tape recorder.
The circuit of a coherer receiver, that recorded the received code on a Morse paper tape recorder.
A radio receiver circuit using a coherer detector (C). The "tapper" (decoherer) is not shown.
A radio receiver circuit using a coherer detector (C). The "tapper" (decoherer) is not shown.
A coherer with electromagnet-operated "tapper" (decoherer), built by early radio researcher Emile Guarini around 1904.
A coherer with electromagnet-operated "tapper" (decoherer), built by early radio researcher Emile Guarini around 1904.