Design Bandpass Filter 300Hz-3000Hz | 8V Out Voltage

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Discussion Overview

The discussion revolves around the design of a bandpass filter with a frequency range of 300Hz to 3000Hz and an output voltage requirement of less than 8V. Participants explore various resistor and capacitor values provided for the design, discussing the application of relevant formulas and methods to achieve the desired filter characteristics.

Discussion Character

  • Homework-related
  • Exploratory
  • Mathematical reasoning

Main Points Raised

  • One participant outlines the components available for the filter design, including specific values of resistors and capacitors.
  • Another participant suggests that with two equations and four unknowns, arbitrary values must be assigned to some variables to proceed with calculations.
  • Concerns are raised about the reliability of electrolytic capacitors, recommending the use of smaller capacitor values for the design.
  • A participant shares their choice of a fixed capacitance value of 0.47µF and provides specific resistor values of approximately 1K and 100 ohms, indicating a trial-and-error approach.
  • Another participant notes that their combination of 0.47mF and 100 ohms yields a frequency close to the target, suggesting further adjustments with different capacitor values to refine the design.

Areas of Agreement / Disagreement

Participants generally agree on the need for trial and error in the design process, but there is no consensus on the optimal values for components or the best approach to take.

Contextual Notes

Participants express uncertainty regarding the reliability of certain capacitor types and the implications of their choices on the filter's performance. The discussion includes various assumptions about component values and their effects on the filter's frequency response.

Who May Find This Useful

Students and hobbyists working on electronic circuit design, particularly those focused on filter design and component selection.

kadzuki2
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Homework Statement



I have to design a bandpass filter (300Hz to 3000Hz). I have been given a variety of resistors and capacitors to work with.

Oh yes, another thing is that i need an output voltage that's <8V. I'm cascading it with another IC.

Capacitors - 10nF, 0.1µF, 0.33µF, 0.47µF, 1µF, 4.7µF, 100µF, 220µF

Resistors - 100, 330, 1K, 3.3K, 4.7K, 5.6K, 10K, 22K, 47K

I have tried using my textbooks as a reference and i used a given example. Then i tried working from there on...

Homework Equations



Some of the formulas given are.. (With reference with my http://img380.imageshack.us/img380/9781/image3kq1.png" )

http://www.testdesigner.com/include/math/images/-1926637852.png

http://www.testdesigner.com/include/math/images/639695238.png

The Attempt at a Solution



I have tried using those formulas, however the best i got was either very small resistance with high capacitance or vice versa.

Am i doing it the right way?
 
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Since you have 2 equations with 4 unknowns, you must assign arbitrary values to 2 of the unknowns.
Electrolytic capacitors are not reliable and should be used mainly as bypass or coupling elements.
I suggest that you choose small values for the capacitors and calculate the value of the resistors.
 
Yep, thanks!

I used a fixed value of 0.47µF for the capacitance. Got [tex]\approx[/tex] 1K and 100 for the resistances :smile:

It's just a matter of trial and error i guess.
 
kadzuki2 said:
Yep, thanks!

I used a fixed value of 0.47µF for the capacitance. Got [tex]\approx[/tex] 1K and 100 for the resistances :smile:

It's just a matter of trial and error i guess.

.47mF and 100 ohm give 3388hz which is close, might want to use 0.1mF and some combination of resistors to get closer for you homework! Don't know your teacher. You give 90% of the answer might score you 90% of the points!
 

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