Need help, Series RLC resonance circuit, not getting high voltage

AI Thread Summary
The discussion revolves around building a series RLC circuit for generating a strong magnetic field, aiming for high voltage at resonance. The user calculated a resonant frequency of 148 kHz and expected a voltage of approximately 108 V rms across the capacitor, but only measured about 60 V pk-pk and 20 V max. Concerns were raised about the limitations of the square wave signal and the functional generator's inability to supply sufficient current. Suggestions included testing the circuit with a sine wave instead of a square wave to achieve better resonance. The conversation highlights the importance of power supply capabilities and signal purity in achieving desired circuit performance.
kougou
Messages
80
Reaction score
0
Hi all.

I am currently building a series RLC circuit as a magnetic field transmitter. Because I want to have a strong magnetic field, I need high voltage by making the circuit at resonance.
Here are the parameter I used:
L:1.15mH
R: 50 (internal resistance from functional generator )+ 0.58 (from inductor)
C: 1 nf.

Using equation the equations w0=1/sqrt(LC), and Vc= Q Vs= 1/R*sqrt(L/C)*vs,
w0=148kHz, and Q=21.2V, and Vs=5V(square wave), so voltage across capacitor should be around 108 V rms.

But using the oscilloscope, the V pk-pk voltage measured is only about 60 V, Vmax is about 20V.

So, why am I not getting the calculated result?
 
Physics news on Phys.org
A square wave is not a pure signal is it?
What happens when you put a range of frequencies into a resonator?
It could also be that your voltage source cannot provide more than 20V.
 
Simon Bridge said:
A square wave is not a pure signal is it?
What happens when you put a range of frequencies into a resonator?
It could also be that your voltage source cannot provide more than 20V.


Thank you for your reply
The source is square wave, and it's jumping from 0 V to 5V. But the resonance voltage across the capacitor should be 5*Q=108V rms. One possiblity is that the functional generator doesn't provide that much current.
Besides that,
I don't know why my circuit doesn't know. Do you have any idea.
 
You are going to be restricted by the available power yes.
Have you tried driving the circuit with a sine wave?
 
Thread 'Motional EMF in Faraday disc, co-rotating magnet axial mean flux'
So here is the motional EMF formula. Now I understand the standard Faraday paradox that an axis symmetric field source (like a speaker motor ring magnet) has a magnetic field that is frame invariant under rotation around axis of symmetry. The field is static whether you rotate the magnet or not. So far so good. What puzzles me is this , there is a term average magnetic flux or "azimuthal mean" , this term describes the average magnetic field through the area swept by the rotating Faraday...
Back
Top