#lc circuit

[hardmoonier]

Why is It Named LC Circuit?

Where the circuits have L, C elements, so what is L? C? In theory, an LC circuit is also called a tank circuit, a tuned circuit or resonant circuit is an electric circuit built with a capacitor denoted by the letter ‘C’ and an inductor denoted by the letter ‘L’ connected together. That is, a combined circuit of capacitor and inductor. When get its meaning, you will have another question: where LC circuits used? You can get the answer from What is the Purpose of LC Circuits?

[apogeewebelectronicblog]

This animation demonstrates the operation of the LC circuit (RLC circuit without resistors). You can learn more about RLC circuit at Apogeeweb!

[s33]

Animated diagram showing the operation of a tuned circuit (LC circuit). The capacitor stores energy in its electric field E and the inductor stores energy in its magnetic field B (green). This jerky animation shows "snapshots" of the circuit at progressive points in the oscillation. The oscillations are slowed down; in an actual tuned circuit the charge oscillates back and forth tens of thousands to billions of times per second.

In electronics an LC circuit, also called a resonant circuit, tank circuit, or tuned circuit, consists of two electronic components connected together; an inductor, represented by the letter L, and a capacitor, represented by the letter C. The circuit can act as an electrical resonator, an electrical analogue of a tuning fork, storing energy oscillating at the circuit's resonant frequency.

This is one of the clearest ways that I have come across to visualize the relationship between electricity and magnetism. On the right, the capacitor plates emphasize the polar nature of EM, so that electric force is a metaphor for binary switching - a bridging across a gap which inverts and imitates.

On the left, the induction coil emphasizes the 'tropic' nature of EM. The magnetic field arises as a summary of the turns, like a squaring of all of the possible orientations and angles. The turningness is juxtaposed against the flowing-ness, which are both juxtaposed against the separation and ratio-ness of the Electric side.

Of course, through Relativity, we can understand (or try to) that both the Electric and Magnetic fields are identical except that they are observed through perpendicular frames of reference. If you are synchronized to the current flow, then it is an electric circuit of positive and negative charge interactions. If you are synchronized to the resistance of the flow, then it is a magnetic field of North/South attraction-repulsion.

The deeper issue for me is really what is happening underneath all of the arrows and theory. What was actually being observed to oscillate when we first measured the frequency of a beam of light? Is it a needle of a magnetic meter? Unlike sound waves which can be said to be collisions of molecules, the energy of electromagnetic waves seems to be more like a propensity for matter to glow, spark, and change direction. It is the Promethean vibration into sensory awareness and motive expression. Matter becomes more transparent to itself, more able to ignore gaps, resistance, and gravity.

EDIT: What electromagnetism seems to really be is something like 'the phenomenalization of matter', or the twisting/stretching of inertial frames.

[ilectureonline]

Physics - Inductance (LC circuit)

Find the current in an LC circuit as a function of time and as a function of charge.

[tymkrs]

Question from a Reader

A reader of the tumblr asked the following:

"Anyways I've always wondered about coils and caps, but what I do is I rectify the power I'm generating with rotating mag fields with a full wave bridge rectifier then I fill a cap, then pulse discharge the cap. Would this be similar to a simple LC tank circuit? The only thing is that there is a FWBR between the coil and cap, and so is it possible to have a resonantly tuned LC tank circuit in which the cap can't bounce back it's charge to the coil because of the FWBR's 1 way flow."

Answer:

So I'm just thinking through this, not giving a professional answer (since I'm the last person you'd want to ask about a textbook solid answer on electronics), but...(and I'm thinking out loud here)

Rotating magnetic fields are sending a signal through a bridge rectifier, leaving you with a DC signal, that charges a capacitor which you then discharge.  

*Oh I see what you mean...FWBR = full wave bridge rectifier*  

I posited this question to the Tymkrs IRC (on Afternet) and @mgburr says it sounds like you're making a pulse generation circuit/charge pump:  "It sounds a lot like using coils to pick up the generated field, turn that into a micro pulse, then build it across the cap/diode network."  Also it sounds like a voltage multiplier: In the front is an AC source, but could conceivably be a set of coils picking up a magnetic movement.   http://en.wikipedia.org/wiki/Voltage_multiplier

And I don't *believe* it can be possible to have a resonantly tuned LC tank circuit where the capacitor doesn't bounce its charge back because to be "resonant" it needs to be able to "bounce back and forth".  

More question: "Also once resonance has been achieved with a spinning rotor past a coil to generate power rectified to charge a capacitor, since this should minimize current flow into the capacitor, wouldn't this eliminate opposing fields dictated by Lenz's law that would normally slow down a gen rotor?, caused by current flowing from the gen coil? And further more if the capacitor is discharged at the correct rate would that small current remain small?"

Mike Burr (@mgburr) helped with this question as he did with the last:  

"If you have a load attached to a coil, and are spinning a rotor near the coil, Lenz's law on magnetic fields dictates that you will have a mechanically resistive effect in that as the rotor approaches the coil, it will be more difficult to move through the field, as it's collapsing.  He's postulating that setting up the rotational speed, equal to the field collapse rate, so that there is no longer the collapsing field to deal with, then it should be easier to move.  In perfect theory this would be close, however..."

*parsing discharged capacitor section*

"The resistive nature of the wire, along with the inherent resistance of the capacitors(ESR) means that it would not truly "hold" the charge.  It would bleed off at some rate.  This would cause flow and fields do "re-develop" in the coils that could still oppose the turn of the rotor through the coil field."

Does this help?

@atdiy/@tymkrs