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The regenerative circuit (or self-regenerative circuit') allows a signal to be amplified many times by the same vacuum tube or other active component such as a field effect transistor. In electronics, a vacuum tube (U.S. and Canadian English) or (thermionic) valve (outside North America) is a device generally used to amplify, or otherwise modify, a signal by controlling the movement of electrons in an evacuated space. ...
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The field-effect transistor (FET) is a transistor that relies on an electric field to control the shape and hence the conductivity of a channel in a semiconductor material. ...
Description
 Regenerative Receiver Schematic Regenerative circuits were employed in early radio receivers, offering selectivity and sensitivity far beyond that available from a crystal radio receiver. Regenerative circuits were a great milestone in radio history. The secret to the regenerative radio receiver operation was the carefully controlled positive feedback. This also allowed the receiver to oscillate, allowing CW (Morse code) to be heard as beeps. The regenerative receiver is theoretically as sensitive as any radio can be, however, the adjustments are critical, and must be continuously monitored during listening. If misadjusted the receiver can transmit interference. Regenerative Receiver Circuit File links The following pages link to this file: Regenerative circuit Categories: User-created public domain images ...
Regenerative Receiver Circuit File links The following pages link to this file: Regenerative circuit Categories: User-created public domain images ...
The crystal radio receiver (also known as a crystal set) was first built circa 1900 by Greenleaf Whittier Pickard, who used crystalline minerals to detect radio signals. ...
One of the most famous quotations about history and the value of studying history, by Spanish philosopher, George Santayana, reads: Those who cannot remember the past are condemned to repeat it. ...
For other uses, including Audio feedback, see Feedback (disambiguation) In cybernetics and control theory, feedback is a process whereby some proportion or in general, function, of the output signal of a system is passed (fed back) to the input. ...
1922 Chart of the Morse Code Letters and Numerals Morse code is a method for transmitting information, using standardized sequences of short and long marks or pulses — commonly known as dots and dashes — for the letters, numerals and special characters of a message. ...
Regenerative receiver The inventor of FM radio, Edwin Armstrong, patented the regenerative circuit (invented while he was a junior in college, and patented 1914), the Super-regenerative circuit (patented 1922), and the Super Heterodyne receiver (patented 1918). Lee De Forest filed a patent in 1916 that became the cause of a contentious lawsuit with the prolific inventor Armstrong, whose patent for the regenerative circuit had been issued in 1914. The abbreviations FM, Fm, and fm may refer to: Electrical engineering Frequency modulation (FM) and its most common applications: FM broadcasting, used primarily to broadcast music and speech at VHF frequencies FM synthesis, a sound-generation technique popularized by early digital synthesizers Science Femtometre (fm), an SI measure of length...
Edwin Howard Armstrong Edwin Howard Armstrong (December 18, 1890 – January 31, 1954) was an American electrical engineer and inventor. ...
Lee De Forest patented a three-electrode version of the Audion. ...
1916 (MCMXVI) is a leap year starting on Saturday (link will take you to calendar) // Events January-February January 1 -The first successful blood transfusion using blood that had been stored and cooled. ...
1914 (MCMXIV) is a common year starting on Thursday. ...
The lawsuit lasted twelve years, winding its way through the appeals process and ending up at the Supreme Court. The Court ruled in favor of De Forest, although the experts still disagree about whether the correct judgement had been issued. The regenerative radio made the most out of very few parts. When the parts became easier to obtain, the superheterodyne receiver replaced it for all serious work. The superheterodyne receiver is the most common receiver in use today. The supreme court in some countries, provinces, and states, is the highest court in that jurisdiction and functions as a court of last resort whose rulings cannot be appealed. ...
The Superheterodyne receiver (or to give it its full name, The Supersonic Heterodyne Receiver – usually these days shortened to superhet) was invented by Edwin Armstrong in 1918. ...
Operating limits Quality of a receiver is defined by its sensitivity and selectivity. For a single-tank TRF (tuned radio frequency) receiver without regenerative feedback, bandwidth = frequency/Q, where Q is tank "quality" defined as Q=Z/R, Z is reactive impedance, R is resistive loss. Signal voltage at tank is antenna voltage multiplied by Q. The Tuned Radio Frequency Receiver (short TRF) was invented by Edwin Armstrong in 1918. ...
Positive feedback compensates the energy loss caused by R, so we may express it as bringing in some negative R. Quality with feedback is Qreg = Z/(R-Rneg). Regeneration rate is M = Qreg/Q = R/(R-Rneg).
Obviously, M depends on stability of amplification and feedback coefficient, because if R-Rneg is set less than Rneg fluctuation, it will easily overstep the oscillation margin. This problem can be partly solved by "grid leak" or any kind of automatic gain control, but the downside of this is surrendering control over receiver to noises and fadings of input signal, which is undesirable. Note that modern semiconductors offer much more stability than vacuum tubes of the 1920s.
Actual numbers: To have 3 kHz bandwidth at 12 MHz (short waves travelling all around Earth) we need Q=F/f = 4000. A two-inch coil of thick silvered wire wound on a ceramic core may have Q up to 400, but let's suppose Q = 100. We need M = 40, which is attainable even without AGC, if amplification/feedback control is smooth enough.
Super-regenerative receiver The superregenerative receiver uses a quenching oscillator to produce very high positive regeneration of the radio amplifying stage, while quenching or keying the built up regenerative oscillation at an ultrasonic rate. This further improves the gain of the receiver while simplifying adjustment.
On the other hand, a superregenerative system has an inherent contradiction limiting its use to relatively free and clear bands. Due to Nyquist's theorem its quenching frequency must be at least twice the signal bandwidth. But quenching with overtones acts further as a heterodyne receiver mixing additional unneeded signals from those bands into the working frequency. Thus the overall bandwidth of superregenerator cannot be less than 4 times that of the quench frequency, assuming the quenching oscillator produces an ideal sinewave. The Nyquist-Shannon sampling theorem is the fundamental theorem in the field of information theory, in particular telecommunications. ...
In telecommunications, to heterodyne is to generate new frequencies by mixing two or more signals in a nonlinear device such as a vacuum tube, transistor, or diode mixer. ...
Coils A Tesla coil is a high-voltage, air-core, self-regenerative resonant transformer that generates very high voltages at high frequency, named after its inventor Nikola Tesla. This coil is part of Tesla's wireless transmission of electric power distribution system (US1119732 - Apparatus for Transmitting Electrical Energy 1902 January 18). A Tesla coil is a category of disruptive discharge coils, named after their inventor, Nikola Tesla. ...
The volt (symbol: V) is the SI derived unit of electric potential difference. ...
A transformer is an electrical device that transfers energy from one electrical circuit to another by magnetic coupling without using any moving parts. ...
This article may be too technical for most readers to understand. ...
Nikola Tesla (July 10, 1856 – c. ...
Wireless energy transfer is wireless transfer of electromagnetic energy via electromagnetic induction. ...
1902 (MCMII) was a common year starting on Wednesday (see link for calendar). ...
January 18 is the 18th day of the year in the Gregorian Calendar. ...
Patents - Armstrong, E. H., U.S. Patent 1113149, Wireless receiving system, 1914.
- Armstrong, E. H., U.S. Patent 1342885, Method of receiving high frequency oscillation, 1922.
- Armstrong, E. H., U.S. Patent 1424065, Signalling system, 1922.
- Barden, R. A., U.S. Patent 2211091, Superregenerative magnetron receiver, 1940.
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