Superregenerativ modtager
Den superregenerative modtager var især populær i radiofoniens barndom (1920'erne-1950'erne). Den har forbavsende god selektivitet og forstærkning.
Den kan være svær at benytte, da den let går i selvsving (den "hyler"). Selvsving undgås ved benytte quenching.[1] Kun én transistor/elektronrør anvendes normalt i radioforsatsen og den har lavt strømforbrug.
Eksperimenter med krystaldetektorer og en strømkilde er formentlig årsagen til, at dioder med negativ differentiel modstand blev opdaget bl.a. 190x, 1908, 1910 - og bredt offentliggjort omkring 1924 af flere. Apparatet eller modtagerprincippet blev kaldt Crystdyne, Cristadyne eller Crystodyne. [2][3] [4] [5] [6] [7] Disse "sære" dioder, kan med den rette justering og kredsløb, få et krystalapparat til at fungere som en superregenerativ modtager, radiosender - eller blot et standard krystalapparat.
Kilder/referencer
- ^ Matematisk orienteret; virkemåde: eix.co.uk: Designing Super-Regenerative Receivers. By Dr Eddie Insam. Published In Electronics World: April 2002 Citat: "...Super-Regenerative radio designs have been around for well over 60 years, and hundreds of circuits have been published, usually with little or no description on how they work. Eddy Insam dispels the magic and explains the details...This is the traditional name given to the process of stopping and restarting the detector after each sample. It comes from the fact that the LC tank needs to be “quenched” or stopped of oscillations after it has reached full swing..."
- ^ G. W. Pickard, "How I Invented the Crystal Detector". Electrical Experimenter, vol. VII, no. 4, p. 325, Aug. 1919 Citat: "...In 1898, when my work in Radio-communication began, there was but one detector—the coherer...In the period 1902 to 1906, I tested many different minerals and combinations, including magnetite, pyrite, galena, molybdenite, silicon and zincite...Oscillating Crystal Detectors. The last word on crystal detectors and their uses has yet to be written. For example, it may be of interest to know that they can be made to OSCILLATE, under proper circuit conditions, and I have found it possible to receive intelligible signals from UNDAMPED wave stations across the Atlantic, on a simple contact between a fragment of galena and a fine wire..."
- ^ God information om anvendelse af dimser med negativ modstandskarakteristikker, før de blev opdaget i tunneldioder i 1957: Cristadyne: Semiconductor archaeology or tribute to unknown precursors Arkiveret 17. marts 2013 hos Wayback Machine Citat: "...In 1923, Oleg Losev [O. V. Lossev, Lossew] (1903-1942) ( See link below ) managed to make a high frequency generator using such a detector. But it was polarized. This indicates that this diode had a characteristic curve in which a negative slope was present. And this makes one think of the tunnel effect diode invented a half a century later...These layouts where part of what one called CRYSTADYNE [eller Cristadyne, Crystodyne ] systems. But in those days, the technical performance and industrial ease of the new increasing valve technology made these layouts to be ignored, and then forgotten..."
- ^ The Wireless World and Radio Review. October 1, 1924 and October 8, 1924: "The Crystal As A Generator And Amplifier" by Victor Gabel.
- ^ earlyradiohistory.us: Radio News, September, 1924, pages 294-295, 431: The Crystodyne Principle Citat: "...SEVERAL experimenters have observed that some contacts, such as crystal and metal or crystal and carbon generally employed as detectors may produce undamped oscillations of any frequency, exactly as the vacuum tube oscillator. The same contact may also be utilized as an amplifier. Oscillating crystals are not new since they were investigated as far back as 1906 by well known engineers, but it was not until lately that a Russian engineer, Mr. O. V. Lossev, succeeded in finding some interesting uses for oscillating crystals..."
- ^ earlyradiohistory.us: Radio News, September, 1924, page 291: A Sensational Radio Invention By HUGO GERNSBACK Citat: "...Stated in a few words, the invention encompasses an oscillating crystal...In other words, THE CRYSTAL NOW ACTUALLY REPLACES THE VACUUM TUBE. That this is a revolutionary radio invention need be emphasized no further. [Her var Hugo Gernsback dog langt forud for sin tid]...We can not only detect with the crystal, but we can also amplify with it...we can now also transmit with the Crystodyne, and, as a matter of fact, a number of students in Russia have actually sent messages with such sets over distances of more than three-quarters of a mile during the past few months..."
- ^ beatriceco.com: Bell Labs – The Transistor – Other Claims to the Invention Arkiveret 21. december 2013 hos Wayback Machine Citat: "...This effect, he stated, was discovered by Dr W. H. Eccles in 1910, and remarked: “It is hard to realize that it took about ten years for practical active crystal-diode circuits to appear, in spite of Ditcham's reminder—circuits that included both RF and AF amplification...Most of the credit for creating practical devices [of this kind] goes to O. V. Lossev of Russia, whether or not he knew of Eccles' pioneer work a decade earlier..."
Eksterne henvisninger
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- Bedste – af Charles Kitchin: electronics-tutorials.com: Regenerative radio receiver Citat: "...The radio described here is a two band short wave receiver which is both very sensitive and very portable. It receives AM, single sideband (SSB), and CW (code) signals over a frequency range of approximately 3.5 to 12MHz..."
- "En superregenerativ modtager Følsomhed 0,5uV", Dansk OZ oktober 1995, s.562-565 Arkiveret 26. januar 2019 hos Wayback Machine. Der er også lidt historisk om den superregenerative modtager.
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Medier brugt på denne side
Forfatter/Opretter: Everaldo Coelho (YellowIcon);, Licens: LGPL
Et ikon fra Crystal-temaet
Forfatter/Opretter: Charly Whisky, Licens: CC BY-SA 4.0
Wiring of an ancient receiver (in German: so called Reflexaudion)
Schematic diagram of a "Crystodyne" negative resistance zinc oxide point-contact diode oscillator invented by Russian scientist Oleg Losev in 1923, published in an American radio magazine. Losev used zinc oxide diodes to build the first semiconductor amplifiers and negative resistance devices, which he used to construct solid state radio transmitters and regenerative and superheterodyne radio receivers, 25 years before the invention of the transistor. However Losev's achievements were overlooked because of the popularity of vacuum tube technology, and were forgotten until they were rediscovered in recent decades.
This is the schematic diagram of the oscillator shown in Crystodyne zincite oscillator - top.png and Crystodyne zincite oscillator - side.png, built by Hugo Gernsback in New York to Losev's instructions. It can produce radio frequency output up to a few megahertz. The active device is the "cat's whisker" diode D, consisting of a crystal of zincite (zinc oxide) with its surface lightly touched by a steel wire on an adjustable arm. It is biased into its negative resistance region by a DC voltage of 4 - 30 volts applied by battery B and potentiometer R. The negative resistance of the diode excites oscillation in the series tuned circuit, consisting of capacitor C1 and variometer inductor L1. Before operation, a sensitive contact point must be found on the surface of the crystal. To do this switch K is turned to the upper position, which switches a second tuned circuit in, L2 and C2 which oscillates at audio frequency. The wire is dragged across the surface of the zincite crystal until a tone is heard in the earphones, indicating the oscillator is working. Then switch K is turned back to the lower position, switching the RF tuned circuit in. The component values from the source are R = 3 kΩ, L1 = 5 mH, C1 = 10 pF, L2 = 1 H, C2 = 2 mF. With these values the frequency of oscillation is approximately
