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

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Discussion Overview

The discussion revolves around a series RLC circuit being built as a magnetic field transmitter, focusing on achieving high voltage at resonance. Participants explore the parameters used in the circuit design and the discrepancies between calculated and measured voltages.

Discussion Character

  • Technical explanation, Debate/contested, Experimental/applied

Main Points Raised

  • One participant describes the circuit parameters (L: 1.15mH, R: 50 + 0.58, C: 1 nf) and calculates the expected resonance voltage across the capacitor to be around 108 V rms based on the quality factor (Q).
  • Another participant notes that a square wave is not a pure signal and questions the effects of applying a range of frequencies to a resonator.
  • Concerns are raised about the voltage source potentially being unable to provide more than 20V, suggesting that the functional generator might be a limiting factor.
  • One participant proposes that the circuit might not be functioning as expected and asks for ideas on troubleshooting.
  • Another participant suggests that the available power could be a restriction and recommends trying to drive the circuit with a sine wave instead of a square wave.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the source of the voltage discrepancy, including the nature of the input signal and the limitations of the power supply. The discussion remains unresolved with no consensus on the cause of the issue.

Contextual Notes

Participants mention potential limitations related to the functional generator's current capacity and the effects of using a square wave versus a sine wave, but these aspects remain unexplored in detail.

kougou
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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?
 
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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?
 

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