Finding the component values of a RLC circuit

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SUMMARY

This discussion focuses on methods to determine the values of components in a series RLC circuit using an oscilloscope, signal generator, and a 10-ohm resistor. The resistor value is found using the voltage divider equation: Vout / Vin = R2 / (R1 + R2). To find the inductor and capacitor values, the user is advised to connect only the LC part of the circuit and apply a low-frequency square wave. By observing the waveform and utilizing XY mode on the oscilloscope, the characteristic frequency can be measured, allowing for the calculation of the inductor and capacitor values based on the derived frequencies.

PREREQUISITES
  • Understanding of series RLC circuits
  • Familiarity with oscilloscopes and their XY mode
  • Knowledge of signal generators and waveform characteristics
  • Proficiency in using voltage divider equations
NEXT STEPS
  • Learn how to use an oscilloscope in XY mode for component analysis
  • Research the characteristics of square wave signals in RLC circuits
  • Study the relationship between frequency and impedance in inductors and capacitors
  • Explore advanced techniques for measuring inductance and capacitance
USEFUL FOR

Electronics enthusiasts, electrical engineers, and students studying circuit analysis who seek to accurately measure and understand the behavior of RLC circuits.

Strides
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What methods could I utilise to find the individual values of the components - resistor, inductor and capacitor - of a series RLC circuit using an oscilloscope, signal generator and 10 ohm resistor. Where each component can be isolated in order to find the voltage etc.

I've already found the value of the resistor component by connecting it in series with the 10 ohm resistor, finding the voltage difference using the oscilloscope and then using the following equation:

Vout / Vin = R2 / (R1 + R2)

However I'm not sure how to find the other components, thanks for all the help in advance.
 
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Strides said:
Vout / Vin = R2 / (R1 + R2)

Just use the same equation with R1 replaced by Z1 (which may be jωL or 1/jωC).
 
Let's assume that your signal generator can generate both sine waves and square waves and supports a low impedance output. You already have the resistor value.
Now connect only the LC part of the circuit across the signal generator outputs, and give a very low frequency square wave as an output. Try to observe the waveform at the node between the inductor and the capacitor. You should see some ripples on the edge of every square wave. That is the characteristic frequency of the LC combination. Now, the only thing you need to do is to measure the inductor or the capacitor frequency separately. Use the resistor that you have in series with the one of the inductor or the capacitor. Now, to measure the inductance, you have to put the scope in XY mode. X should show the voltage across the resistor + inductor series combination. Y should show the voltage across inductor only. If you sweep across frequencies, you will get an unskewed ellipse/circle at some particular frequency. This is the 3dB frequency for the inductor. You can derive the values of the inductor and capacitor from the 2 frequencies.
 

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