Verator front end

[Verator]

And what a transformer? This is only the connection of coils and nothing more. I did so, nothing changes. The transformer is not to blame.
The coil affects more resistance, he has a shunt. You can change the resistance of the resistor 10 to 1000K - nothing will change.
The parasitic capacitance of the resonance at high frequency. There's capacity reaches 500-2000pf Depends on how many turns.

[Davor]

Not exactly. A circuit in post #104 does not represent a coil working as a pickup. When you simulate a coil as a pickup, you may use a loosely coupled transformer, or much easier a voltage source in series with a coil. When a coil is subjected to a changing magnetic field, it produces a voltage. Therefore a search coil connected as a tank does not respond as a tank with shunt source, but as an L topology low-pass filter.

[Derx]

yes, Davor

[Verator]

Well, the transformer and the "poor connection"? Not convincing. It seems to me that there is no difference as the voltage applied to the coil, in parallel or in series. There's also a resistor in order and is not to shunt inductance. You can put a 100k resistor.In the coil voltage does not occur, and the induced current. Voltage - it's leash mirror current.

[Verator]

Amplitude linearity coil is not true. It may not be smooth. Inductance do not work on a range of frequencies. Voltage on the coil will increase linearly with increasing frequency. The law of nature.

[Davor]

What you observed is true, yet the mechanism by which it happens is not. Induced EMF is what we are using here. It may be easier to grasp the concept by an analogy of a rotating coil in a constant magnetic field. If "f" represents the frequency of rotation we have V = 2 π f N A B sin(2 π f t)

So instead rotating a coil we have a magnetic field "rotating" at frequency "f" and everything fits nicely.

[Verator]

If "f" represents the frequency of rotation we have V = 2 π f N A B sin(2 π f t)

I figured with your model. Now I understand the question. I thought that there is no difference as to apply the EMF spool. I would like to ask what is the model of inductance. Can not you get it through your courtesy.

[Davor]

The varicoil model is completely contained in my post #26. It is a hierarchical model, so the model is contained in Varicoil.asc
It appears as ideal inductance with value equal to the control voltage. Hence, 1mV results with 1mH inductance. So unlike sweeping a parameter to change inductance from one pass to the next, I can gradually change inductance within a single go of simulation.
Otherwise it sucks for the fact you can't use it for circuits with mutual inductance, and can not assign any coupling with other inductances. For single inductance cases it is OK.

[Verator]

Thank you. But where to find a description of this model is used. I can not yet understand its characteristics.

[Davor]

Which one? The varicoil? Just open the Varicoil.asc and you'll see.

[Verator]

It was possible to obtain an acceptable option

[Verator]

You can still apply and so the inclusion of the coil. RL = 50 CL = 500pF

[Davor]

OK, that's more like a MD pickup. So you see the thing that confuses people is the peak and they say it is a tank at resonance, while in reality it is a 2nd order low pass filter with Q much greater than 1/2.

I guess you are already trying alternative ways of connecting a coil to obtain better noise and less phase variation? I'm sure the next Verator is going to have a much better front end

[Verator]

There is no doubt that it is necessary to pay more attention. In the current version of this type of receiver is not suitable because of the high harmonics.