Using a DC Choke in Resonant Circuits w/ Capacitors

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SUMMARY

A DC choke can be used in a resonant circuit with a capacitor, but its effectiveness depends on the choke's design and application. When connected in series with a capacitor, the resonance frequency can be calculated based on the choke's inductance and the capacitor's capacitance. For instance, an 8 Henry inductor in series with a 0.879 µF capacitor resonates at 60 Hz, while a 0.22 µF capacitor resonates at 120 Hz. This configuration can lead to increased hum in power supplies, particularly those utilizing a full wave rectifier, counteracting the choke's intended purpose of reducing hum.

PREREQUISITES
  • Understanding of resonant circuits
  • Knowledge of inductance and capacitance
  • Familiarity with DC chokes and their applications
  • Basic principles of frequency calculation in electrical circuits
NEXT STEPS
  • Research the principles of resonant frequency calculation in LC circuits
  • Explore the differences between DC chokes and standard inductors
  • Learn about the impact of core saturation on choke performance
  • Investigate methods to mitigate hum in power supply circuits
USEFUL FOR

Electrical engineers, hobbyists designing resonant circuits, and anyone involved in power supply design and noise reduction techniques.

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Can a DC choke (inductor) filter be used in a resonant circuit with a capacitor? If connected in series with a capacitor will the two resonate, or will the signal passed be half wave? I thought all inductors can be interchangeable but some have certain applications such as DC applications.
 
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Depends on the type of choke. Some chokes are just plain inductors, others have magnetic cores that absorb certain range of frequencies.
 
Chokes used for filtering DC have a gap in the core so the DC doesn't saturate the core. Otherwise, they are just inductors.

For example, if you put a 8 Henry inductor in series with 0.879 uF you would get resonance at 60 Hz. Or put it in series with 0.22 uF and it would resonate with 120 Hz.

This would be pretty dramatic in a power supply with a 120 Hz component from a full wave rectifier. It would produce a big increase in hum when the function of the choke is normally to reduce hum.
 

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