[Amps] What is a Tank Circuit?

[Colin Lamb]

The question is why is an LC circuit often called a tank circuit.

One possible answer is contained in a paragraph in Wikipedia regarding 
LC circuits, which is as follows:


    "History

The first evidence that a capacitor and inductor could produce 
electrical oscillations was discovered in 1826 by French scientist Felix 
Savary <http://en.wikipedia.org/wiki/Felix_Savary>.^[2] 
<http://en.wikipedia.org/wiki/LC_circuit#cite_note-Blanchard-2> ^[3] 
<http://en.wikipedia.org/wiki/LC_circuit#cite_note-3> He found that when 
a Leyden jar <http://en.wikipedia.org/wiki/Leyden_jar> was discharged 
through a wire wound around an iron needle, sometimes the needle was 
left magnetized in one direction and sometimes in the opposite 
direction. He correctly deduced that this was caused by a damped 
oscillating discharge current in the wire, which reversed the 
magnetization of the needle back and forth until it was too small to 
have an effect, leaving the needle magnetized in a random direction. 
American physicist Joseph Henry 
<http://en.wikipedia.org/wiki/Joseph_Henry> repeated Savary's experiment 
in 1842 and came to the same conclusion, apparently independently.^[4] 
<http://en.wikipedia.org/wiki/LC_circuit#cite_note-Kimball-4> ^[5] 
<http://en.wikipedia.org/wiki/LC_circuit#cite_note-Huurdeman-5> British 
scientist William Thomson <http://en.wikipedia.org/wiki/William_Thomson> 
(Lord Kelvin) in 1853 showed mathematically that the discharge of a 
Leyden jar through an inductance should be oscillatory, and derived its 
resonant frequency.^[2] 
<http://en.wikipedia.org/wiki/LC_circuit#cite_note-Blanchard-2> ^[4] 
<http://en.wikipedia.org/wiki/LC_circuit#cite_note-Kimball-4> ^[5] 
<http://en.wikipedia.org/wiki/LC_circuit#cite_note-Huurdeman-5> British 
radio researcher Oliver Lodge 
<http://en.wikipedia.org/wiki/Oliver_Lodge>, by discharging a large 
battery of Leyden jars through a long wire, created a tuned circuit with 
its resonant frequency in the audio range, which produced a musical tone 
from the spark when it was discharged.^[4] 
<http://en.wikipedia.org/wiki/LC_circuit#cite_note-Kimball-4> In 1857, 
German physicist Berend Wilhelm Feddersen 
<http://en.wikipedia.org/wiki/Berend_Wilhelm_Feddersen> photographed the 
spark produced by a resonant Leyden jar circuit in a rotating mirror, 
providing visible evidence of the oscillations.^[2] 
<http://en.wikipedia.org/wiki/LC_circuit#cite_note-Blanchard-2> ^[4] 
<http://en.wikipedia.org/wiki/LC_circuit#cite_note-Kimball-4> ^[5] 
<http://en.wikipedia.org/wiki/LC_circuit#cite_note-Huurdeman-5> In 1868, 
Scottish physicist James Clerk Maxwell 
<http://en.wikipedia.org/wiki/James_Clerk_Maxwell> calculated the effect 
of applying an alternating current to a circuit with inductance and 
capacitance, showing that the response is maximum at the resonant 
frequency.^[2] 
<http://en.wikipedia.org/wiki/LC_circuit#cite_note-Blanchard-2> The 
first example of an electrical resonance 
<http://en.wikipedia.org/wiki/Resonance> curve was published in 1887 by 
German physicist Heinrich Hertz 
<http://en.wikipedia.org/wiki/Heinrich_Hertz> in his pioneering paper on 
the discovery of radio waves, showing the length of spark obtainable 
from his spark-gap LC resonator detectors as a function of 
frequency.^[2] 
<http://en.wikipedia.org/wiki/LC_circuit#cite_note-Blanchard-2>

One of the first demonstrations of resonance 
<http://en.wikipedia.org/wiki/Resonance> between tuned circuits was 
Lodge's "syntonic jars" experiment around 1889.^[2] 
<http://en.wikipedia.org/wiki/LC_circuit#cite_note-Blanchard-2> ^[4] 
<http://en.wikipedia.org/wiki/LC_circuit#cite_note-Kimball-4> He placed 
two resonant circuits next to each other, each consisting of a Leyden 
jar connected to an adjustable one-turn coil with a spark gap. When a 
high voltage from an induction coil was applied to one tuned circuit, 
creating sparks and thus oscillating currents, sparks were excited in 
the other tuned circuit only when the circuits were adjusted to 
resonance. Lodge and some English scientists preferred the term 
"/syntony/" for this effect, but the term "/resonance/" eventually 
stuck.^[2] 
<http://en.wikipedia.org/wiki/LC_circuit#cite_note-Blanchard-2> The 
first practical use for LC circuits was in the 1890s in spark-gap radio 
transmitters <http://en.wikipedia.org/wiki/Spark-gap_transmitter> to 
allow the receiver and transmitter to be tuned to the same frequency. 
The first patent for a radio system that allowed tuning was filed by 
Lodge in 1897, although the first practical systems were invented in 
1900 by Italian radio pioneer Guglielmo Marconi 
<http://en.wikipedia.org/wiki/Guglielmo_Marconi>.^[2]" 
<http://en.wikipedia.org/wiki/LC_circuit#cite_note-Blanchard-2>

^So, the first LC circuits were actually contained within Leyden jars.  
Perhaps they were called tanks.

^Or maybe not.

^73,  Colin K7FM