Body
Hi Warren,
"...description of how more voltage is in an LC circuit than is put in."
It's only the peak to peak voltage that's greater than the input voltage which is only the peak voltage. If no loss (infinite quality factor (Q) there's no decay and the negative voltage is then the same as the positive voltage. With no decay the oscillations will never stop. This is only possible in a theoretical circuit using an ideal inductor (L) and an ideal capacitor (C). Ideal components haven't got parasitic parts of L, C or R as do real components and are only used in mathematical models or simulations to make the calculations easier.
"Will the decay characteristic sign wave change, if the inductor is much fatter wire, or even copper tubing? That should lower the resistance, should it not?"
If meaning a sine wave it does change sign at each half period. This happens as the energy oscillates between the capacitor and inductor. Each time the energy is reflected in one of the components the tension and current changes sign. Thicker copper or silver plated copper decreases the resistance. At high frequency only a thin layer of the conductor actually is a play. Thus at HF copper tubing is used of multi-stranded insulated copper wire (Litze wire https://wiki2.org/en/Litz_wire).
The frequency of the oscillations is given by the inductance and capacitance of the circuit. The decay is given by the loss which is the inverse of the goodness or quality factor Q. To slow down the decay more ideal components are needed as they have less loss. A continuous oscillating LC-tank must have energy supplied at the same rate (same power) as it looses energy to keep the peak amplitude steady. Neither more nor less energy is allowed for steady oscillations.
From Wikipedia article (https://wiki2.org/en/LC_circuit https://wiki2.org/en/LC_circuit):
https://wiki2.org/en/File:Tuned_circuit_animation_3_300ms_gif
Animated diagram showing the operation of a tuned circuit https://wiki2.org/en/Tuned_circuit (LC circuit). The capacitor C stores energy in its electric field https://wiki2.org/en/Electric_field E and the inductor L stores energy in its magnetic field https://wiki2.org/en/Magnetic_field B (green). The animation shows the circuit at progressive points in the oscillation. The oscillations are slowed down; in an actual tuned circuit the charge may oscillate back and forth thousands to billions of times per second.
"If such a case is in, fact, true, how large of inductor cross section can we use to optimize the number of cycles of ringing, by eliminating impedance as much as possible?"
This depends on several factors. Only the resistive part of the impedance has to be eliminated. Resonance is happening at the frequency where the capacitive part of the impedance is canceling the inductive part of the impedance thus leaving only the resistive part of the impedance that gives loss. The capacitive and inductive parts of the impedance are zero Ohm (at resonance) as one is positive and the other one is negative.
"This is an air core. What happens if we use, for instance, Metglas core, or something with superior ferro magnetic qualities. Where does the Q factor come in to the equation?"
Using a magnetic conductor as core makes the inductance of the inductor increase when having the same number of turns length and diameter. As the Q factor is the inverse of the loss the Q will decrease when the core has losses. The core has losses if resistive as the induced current in the core is then dissipated as heat. In the measurements the resistive part of the core is seen as a frequency dependent part that increases with the frequency. The skin effect of the wire is also seen that way. A metal glass core has low loss while an air core has no loss. A good magnetic conductor doesn't store much energy as the energy just passes through it. Therefore air gaps are used for storing energy.
"A very basic question. How do we know there is resonance when looking at the scope?"
That's seen if the voltage changes sign across the capacitor. If the circuit is over damped the energy is dissipated before completing even a single oscillation. This is because the resistance is too great. At less resistance there is less damping. If having an electric guitar and an oscilloscope the resonant frequency of a string can be seen when applying energy to the string and then letting go of it. This is also seen as oscillations on the scope. As guitar strings have low loss they keep ringing for a while just like an LC-tank circuit. A guitar string is just a mechanical oscillator. Applying damping (i.e. by touching with a finger) makes the oscillations decay faster.
Regards
Ole
---In [email protected], <schoonersolsticemoon@...> wrote :
Ole Thank you for that very clear, and basic description of how more voltage is in an LC circuit than is put in. That is very useful, and interesting.
It brings questions to mind.
Will the decay characteristic sign wave change, if the inductor is much fatter wire, or even copper tubing? That should lower the resistance, should it not?
If such a case is in, fact, true, how large of inductor cross section can we use to optimize the number of cycles of ringing, by eliminating impedance as much as possible?
This is an air core. What happens if we use, for instance, Metglas core, or something with superior ferro magnetic qualities. Where does the Q factor come in to the equation?
A very basic question. How do we know there is resonance when looking at the scope?
Thank you for your for your help Ole.
Cheers Warren
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On Tue, 30 Oct 2018 at 10:05 PM, onielsen@... [EVGRAY]
<[email protected]> wrote:
Hi Warren,
Here is a video showing how to do it (LC (tank) circuit addendum Part 2 of 2): https://www.youtube.com/watch?v=Ij3I6gZxYEU https://www.youtube.com/watch?v=Ij3I6gZxYEU
Just take an inductor and a capacitor. Charge the capacitor and then discharge it through the inductor and the two components will ring at the resonant frequency of the circuit. The circuit is called an LC-tank and is made of two energy storing components. If there's also resistance in the LC-tank circuit the oscillations will decay. If using standard components they will have resistance which is called parasitic resistance when not intended. This makes any practical LC-tank actually being a lossy LCR-tank.
If instead applying the energy to the inductor the capacitor has to be connected as well as a current source. When letting go the current source (current through the inductor) the energy will oscillate between the inductor and capacitor as in the first example where it was the capacitor that had the initial energy stored.
Regards
Ole
---In [email protected], <schoonersolsticemoon@...> wrote :
Mick Resonance in an LC circuit:
You said it was easy to do.
How do you it?
I would like to do it mechanically, that is with wire sizes, and lengths of coil, so it does not need a special capacitor, or tuning, as the whole thing is, bang on the money, as far as harmonics go, like a well tuned guitar.
Perhaps, I ask for too much, as I hsave not been able to do this yet.
I have read that it is a matter of frequency of the input.
Hopefully my frequency generator might help, as it is adjustable.
Cheers Warren
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On Tue, 30 Oct 2018 at 12:29 PM, Mick mkjekyll@... [EVGRAY]
<[email protected]> wrote:
Hector,
Very true, divide and conquer! Real actual liberal values and fiscal conservative are much the same. Both groups have been co-opted by phony actors who are of neither.
Just tired of all the hate being spread to polarize people such as Kone saying all gun owners or all conservatives should be killed. This is the shit that is destroying our civilization. The media politicizing the murder of people after doing their best for years to spread discontent and hatred on every fucking news show hundreds of times a day. But people want to be polarized into hate groups for some reason.
The TTL carrier comment was to present the question: In a wideband class AB RF amp without a LC tank used for the modulation freq, where is the PF of leading or lagging coming from before the antenna load? Or are you claiming all RF amps even extremely wide-band laboratory amps have an LC tank somewhere such as for the collector bias?
On 10/30/2018 5:46 AM, arkresearch@... mailto:arkresearch@... [EVGRAY] wrote:
Left & right had always being part of one body ......like 2 hands
one jerks it off wile the other puts a gun to its head and blows it up !
calling democrats liberals is like calling a whore house a monastery ..
the word does not fit , neither conservatives on the republicans , nothing to conserve here !
Amen !
(H)