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| Keywords: Popovs first receiver.png radio receivers a simple device that rang a bell when a radio signal was received built by Russian scientist Alexander Stepanovich Popov in 1895 Built as a lightning detector to warn of thunderstorms by registering the radio pulses of lightning strikes Popov demonstrated it before the Russian Physical-Chemical Society in St Petersburg on 7 May 1895 receiving signals from a spark-gap radio transmitter In Eastern Europe Popov is regarded as the first person to communicate by radio and May 7 is celebrated as Radio Day <br /><br /> It used a primitive radio wave detector called a coherer invented in 1890 by Edouard Branly consisting of a glass tube with metal filings between two electrodes The coherer was connected to a wire antenna and also a circuit with a battery left and a relay cylinder center When a radio signal from the antenna arrived at the coherer's electrodes the metal filings became conductive The current from the battery flowed through the coherer and energized the relay closing its contacts and applying the current from the battery to the electromagnet of the electric bell right which pulled its arm over to give the bell a tap To restore the coherer to its receptive state the filings needed to be disturbed by tapping it so when the bell arm sprang back it tapped the coherer automatically resetting it 1960 Retrieved 11 November 2013 from http //www nsa gov/public_info/_files/tech_journals/aleksandr_popov pdf author name redacted Did Alexandr Popov Invent Radio NSA Technical Journal US National Security Agency Bethesda MD Vol 5 No 1 January 1960 p 37 on http //www nsa gov/public_info/declass/tech_journals shtml US National Security Agency website author PD-USGov Uploaded with UploadWizard Coherers Alexander Stepanovich Popov Antique radios Coherer radiotelegraphy receivers | ||||
