STEORN DEMO LIVE & STREAM in Dublin, December 15th, 10 AM

[skcusitrah]

@skcusitrah,
As for the inductance, there's obviously no inductance in the RC circuit we're exploring , so there's no need to bring in this point. As far as the experiment goes, inductance is a non-issue there as well. That is taken care of by the Hall effect current probe.

The parasitic circuit inductance can be ignored if one wishes, but it is there, guaranteed. It is present, and it is affecting your measurements and consequently your calculations.

If by "obvious" you mean not intentional or not visible, then you would be correct. However, the inductance is parasitic and it can not be seen as a discrete component.

Please add up all the wire and component lead lengths 360º around your circuit and let us know what the total is. Every wire adds inductance, and just the solid wire leads on your resistor can exhibit enough inductance to throw off your measurements if not accounted for.

Please explain how it is "obvious" to you that there is no circuit inductance and how it is a non-issue?

How can one say that omitting the parasitic circuit inductance in the calculations is good practice, when its reactance value can be on the order of the resistance of R1 (i.e. XL@ 800kHz=5 Ohms) ?

If it is there (and it is), then it also must appear in your calculations to be correct.

[broli]

The parasitic circuit inductance can be ignored if one wishes, but it is there, guaranteed. It is present, and it is affecting your measurements and consequently your calculations.

If by "obvious" you mean not intentional or not visible, then you would be correct. However, the inductance is parasitic and it can not be seen as a discrete component.

Please add up all the wire and component lead lengths 360º around your circuit and let us know what the total is. Every wire adds inductance, and just the solid wire leads on your resistor can exhibit enough inductance to throw off your measurements if not accounted for.

Please explain how it is "obvious" to you that there is no circuit inductance and how it is a non-issue?

How can one say that omitting the parasitic circuit inductance in the calculations is good practice, when its reactance value can be on the order of the resistance of R1 (i.e. XL@ 800kHz=5 Ohms) ?

If it is there (and it is), then it also must appear in your calculations to be correct.

Sure parasitic inductance is always present. Probably in the pico range.

But even if it was big why would it change anything? Does it create an alternative path for current like the argument with parasitic capacitance? Even with parasitic inductance the measured current would be flowing through the resistance. Using this and input voltage and current a comparison can be made for energy/power. So in the end it doesn't even matter if parasitic inductance. Parasitic capacitance was the main argument with the previous experiments I would take parasitic inductance over it any time.

[skcusitrah]

Sure parasitic inductance is always present. Probably in the pico range.

But even if it was big why would it change anything? Does it create an alternative path for current like the argument with parasitic capacitance? Even with parasitic inductance the measured current would be flowing through the resistance. Using this and input voltage and current a comparison can be made for energy/power. So in the end it doesn't even matter if parasitic inductance. Parasitic capacitance was the main argument with the previous experiments I would take parasitic inductance over it any time.

Actually, that's incorrect on both accounts.

First, I guarantee that the circuit being tested exhibits a minimum of 600nH of parasitic inductance.

Second, what happens to the phase angle between V and I when a significant inductive reactance is introduced into the simple series RC circuit? Is the instantaneous power calculation not highly affected by the relative phase?

[broli]

Actually, that's incorrect on both accounts.

First, I guarantee that the circuit being tested exhibits a minimum of 600nH of parasitic inductance.

Second, what happens to the phase angle between V and I when a significant inductive reactance is introduced into the simple series RC circuit? Is the instantaneous power calculation not highly affected by the relative phase?

Perhaps you haven't looked further than the last two pages. But experimental data shows very strong capacitive behavior almost purely capacitive to be exact.

Just an innocent question. Exactly what do you think is going on at the moment?

[Omega_0]

Guys,

I studied the last sim data posted by Omnibus above.
It has occured to me that everyone is missing a crucial piece from the calculations, which is the energy stored in the capacitor. It is given by 0.5*C*Vc^2

Vc is the voltage across the cap and we have:
Vin = Vr + Vc ,         assuming Vr is the drop across the resistor
or Vc = Vin - Vr
         = Vin - I*R

So Etotal = Er + Ec
          = I^2*R + 0.5*100pF*(Vin-Iin*R)^2

Which will come out exactly equal to Ein = Vi*Ii

Similarly, in case of a coil, the energy stored is 0.5*L*I^2, which should be added in Eout. So even though the real power is dissipated only in the resistor, there is some energy that gets stored during every cycle in the inductor or cap.
If you don't believe me check out the attached modified file. And if you think I'm making some mistake, please let me know.
.