The
Hartley oscillator is an
LAn inductor or a reactor is a passive electrical component that can store energy in a magnetic field created by the electric current passing through it. An inductor's ability to store magnetic energy is measured by its inductance, in units of henries...
CA capacitor or condenser is a passive electronic component consisting of a pair of conductors separated by a dielectric. When a voltage potential difference exists between the conductors, an electric field is present in the dielectric. This field stores energy and produces a mechanical force...
electronic oscillatorAn electronic oscillator is an electronic circuit that produces a repetitive electronic signal, often a sine wave or a square wave.A low-frequency oscillator is an electronic oscillator that generates an AC waveform at a frequency below ≈20 Hz...
that derives its feedback from a tapped
coilA coil is a series of loops. A coiled coil is a structure where the coil itself is in turn also looping.-Electromagnetic coils:An electromagnetic coil is formed when a conductor is wound around a core or form to create an inductor or electromagnet...
in parallel with a
capacitorA capacitor or condenser is a passive electronic component consisting of a pair of conductors separated by a dielectric. When a voltage potential difference exists between the conductors, an electric field is present in the dielectric. This field stores energy and produces a mechanical force...
(the
tank circuit). Although there is no requirement for there to be mutual coupling between the two coil segments, the circuit is usually implemented as such. A Hartley oscillator is essentially any configuration that uses a pair of series-connected coils and a single capacitor (see
Colpitts oscillatorA Colpitts oscillator, named after its inventor Edwin H. Colpitts, is one of a number of designs for electronic oscillator circuits using the combination of an inductance with a capacitor for frequency determination, thus also called LC oscillator. One of the key features of this type of...
for the equivalent oscillator using
two capacitors and
one coil).
Discussion
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The
Hartley oscillator is an
LAn inductor or a reactor is a passive electrical component that can store energy in a magnetic field created by the electric current passing through it. An inductor's ability to store magnetic energy is measured by its inductance, in units of henries...
CA capacitor or condenser is a passive electronic component consisting of a pair of conductors separated by a dielectric. When a voltage potential difference exists between the conductors, an electric field is present in the dielectric. This field stores energy and produces a mechanical force...
electronic oscillatorAn electronic oscillator is an electronic circuit that produces a repetitive electronic signal, often a sine wave or a square wave.A low-frequency oscillator is an electronic oscillator that generates an AC waveform at a frequency below ≈20 Hz...
that derives its feedback from a tapped
coilA coil is a series of loops. A coiled coil is a structure where the coil itself is in turn also looping.-Electromagnetic coils:An electromagnetic coil is formed when a conductor is wound around a core or form to create an inductor or electromagnet...
in parallel with a
capacitorA capacitor or condenser is a passive electronic component consisting of a pair of conductors separated by a dielectric. When a voltage potential difference exists between the conductors, an electric field is present in the dielectric. This field stores energy and produces a mechanical force...
(the
tank circuit). Although there is no requirement for there to be mutual coupling between the two coil segments, the circuit is usually implemented as such. A Hartley oscillator is essentially any configuration that uses a pair of series-connected coils and a single capacitor (see
Colpitts oscillatorA Colpitts oscillator, named after its inventor Edwin H. Colpitts, is one of a number of designs for electronic oscillator circuits using the combination of an inductance with a capacitor for frequency determination, thus also called LC oscillator. One of the key features of this type of...
for the equivalent oscillator using
two capacitors and
one coil). It was invented by
Ralph HartleyRalph Vinton Lyon Hartley was an electronics researcher. He invented the Hartley oscillator and the Hartley transform, and contributed to the foundations of information theory.-Biography:...
, who filed for a
patentA patent is a set of exclusive rights granted by a state to an inventor or their assignee for a limited period of time in exchange for a public disclosure of an invention....
on June 1, 1915 and was awarded patent number
http://patimg2.uspto.gov/.piw?Docid=01356763&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect1%3DPTO1%2526Sect2%3DHITOFF%2526d%3DPALL%2526p%3D1%2526u%3D%25252Fnetahtml%25252FPTO%25252Fsrchnum.htm%2526r%3D1%2526f%3DG%2526l%3D50%2526s1%3D1,356,763.PN.%2526OS%3DPN%2F1,356,763%2526RS%3DPN%2F1,356,763&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page 1,356,763 on October 26, 1920.
Operation
A Hartley oscillator is made up of the following:
- Two inductor
An inductor or a reactor is a passive electrical component that can store energy in a magnetic field created by the electric current passing through it. An inductor's ability to store magnetic energy is measured by its inductance, in units of henries...
s in series, which need not be mutual
- One tuning capacitor
Advantages of the Hartley oscillator include:
- The frequency may be varied using a variable capacitor
- The output amplitude remains constant over the frequency range
- Either a tapped coil or two fixed inductors are needed
Disadvantages include:
- Harmonic-rich content if taken from the amplifier and not directly from the LC circuit.
Note that, if the inductance of the two partial coils and is given (e.g. in a simulator), the total effective inductance that determines the frequency of the oscillation is (coupling factor ):
(see )
Applications
The Hartley oscillator was extensively used on all
broadcast bandBroadcast band commonly refers to several segments of the radio spectrum. In the U.S. the major broadcast bands are:In Europe, North Africa and Asia, longwave radio frequencies between 153 and 281 kHz are used for domestic and international broadcasting....
s including the FM 88-108MHz band. An example is given of the Scott 310E RF oscillator for its FM section.
History
The Hartley oscillator was invented by
Ralph V.L. HartleyRalph Vinton Lyon Hartley was an electronics researcher. He invented the Hartley oscillator and the Hartley transform, and contributed to the foundations of information theory.-Biography:...
while he was working for the Research Laboratory of the Western Electric Company. Hartley invented and patented the design in 1915 while overseeing Bell System's transatlantic radiotelephone tests. In 1946 Hartley was awarded the IRE medal of honor "For his early work on oscillating circuits employing triode tubes and likewise for his early recognition and clear exposition of the fundamental relationship between the total amount of information which may be transmitted over a transmission system of limited band-width and the time required."(The second half of the citation refers to Hartley's work in information theory which largely paralleled
Harry NyquistHarry Nyquist , was an important contributor to information theory.-Personal life:...
.)
See also
- Armstrong oscillator
The Armstrong oscillator is named after the electrical engineer Edwin Armstrong, its inventor. It is sometimes called a tickler oscillator because the feedback needed to produce oscillations is provided using a tickler coil via magnetic coupling between coil L and coil T...
- Colpitts oscillator
A Colpitts oscillator, named after its inventor Edwin H. Colpitts, is one of a number of designs for electronic oscillator circuits using the combination of an inductance with a capacitor for frequency determination, thus also called LC oscillator. One of the key features of this type of...
- Clapp oscillator
The Clapp oscillator is one of several types of electronic oscillator constructed from a transistor and a positive feedback network, using the combination of an inductance with a capacitor for frequency determination, thus also called LC oscillator.It was published by James K. Clapp in 1948...
- Vačkář oscillator
The Czech engineer Jiří Vackář published in 1949 a paper on the design of stable oscillators. As a result of his in-depth analysis of oscillators, he proposed a variant of a Colpitts oscillator, where an additional capacitive voltage divider on the grid input reduces the feedback voltage to the...
- Opto-Electronic Oscillator
An opto-electronic oscillator is an optoelectronic circuit that produces repetitive electronic sine wave and/or modulated optical continuous wave signals....
External links