Hello Simen,
Please let me know the name of the simulation software that you are use.
Thanks in advance.
Mark Wilkinson
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From:
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Sent: Friday, March 26, 2021 7:52 AM
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Subject: [nanovna-users] Why does the two currents in a parallel LC-resonance circuit cancel on a lower frequency than the LC-resonance? #coils #charts #test #teaching #traps #simulation #rant #problem #measurement #learning #circuit
Simulations show Currents do NOT cancel at the Parallel LC-resonance frequency, contrary to what we learn is one of the main characteristics of parallel resonance circuits. Why?
Testing various LC combinations, the two Currents always meet and cancel at a frequency lower than the XL = XC frequency.
?
Micro-Cap 12 (Transient Analysis; Oscilloscope) shows LC-resonans frequency / 1.034 ¡Ö frequency of current cancellation. Moving the input frequency up and down from this point you can find the perfect frequency where the two currents have the same amplitude = cancelling. Down in frequency makes the current through the inductor stronger, up makes the current through the capacitor stronger.
I mostly use RS = 10m Ohm in both the Capacitor and in the low induction Coil. Same is true with RS = 0 Ohm.
LC wise they are perfect(ly fake ;) 0 parasitic L and C. Anyway, the simulation makes no difference; Capacitance added to the inductor gives the same result as if the C was in a separate capacitor; It just moves the LC-resonance to a lower frequency. And the current-cancelling frequency also thereby moves down.
This also correlate to the readings on my nanoVNA; two different frequencies, and I do not understand how to combine them into an ¡°official¡± Parallel LC-resonance circuit.
--
Simen Tobiassen
