test bandpass

Discussion in 'Homework Help' started by sunone, Jan 17, 2011.

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  1. sunone

    Thread Starter New Member

    Jan 11, 2011
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    Hello!
    I have to build a bandpass filter, noise filtering and removing the DC component for a signal, the range is [0.5-5 Hz].

    I am using the following design:
    http://img199.imageshack.us/img199/2947/badnpass.jpg

    Considering my available components (but I am planning
    to use more coherent stuff)
    Part high-pass:
    C1, C2 = 1 microF
    R1 = 450 KOhm
    R2 = 225 kOhm
    Part lowpass:
    R1, R2 = 8.2 KOhm
    C1 = 4.7 microF
    C2 = 2.2 microF
    -------------------------------------------------- --------------
    Here are my questions,
    1. Using a wave generator and an oscilloscope, how do I test that the allowed band is effectively [0.5-5 Hz] ? What differences should I see if I send as an input a square/triangle/pseudo-sinus wave inside and outside the band ?

    3. I need to avoid dual supply amplifier, 'cause the rest of the circuit is aa single supply. Assuming I have some LM386 and LM358, is it correct to just use the bottom circuit in the picture I posted ?

    4. Considering I want to filter a signal coming from a photodiode and a transimpedence amp. removing noise and DC component. Can I stick with the filter I posted, or should I investigate more about Butterworth, Bessel and so on filter .... ?
     
    Last edited: Jan 17, 2011
  2. sunone

    Thread Starter New Member

    Jan 11, 2011
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    Can I kindly receive an explanation why my questions were moved in HOMEWORK HELP ???!?!?!!?
    I can understand that for some of you some of these questions are really easy but for me they are not!!!!!!!
    And browsing among the threads I don't see a big difference between my questions and the questions of the other users!!!! I FOUND THIS BEHAVIOUR REALLY OFFENSIVE.:mad::mad::mad:

    After a Msc in Informatic Engineering and a Ph.d in Applied math for medical imaging, I don't expect to be a genius of electronics because it is just an hobby and I am here to learn. But I found difficult to learn if someone discriminates me for some reasons. Is there a not clear motivation in the rules of the forum ? Can I have explained which part of the forum agreement did I violate ?

    Best regards
     
  3. bertus

    Administrator

    Apr 5, 2008
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  4. t06afre

    AAC Fanatic!

    May 11, 2009
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    As you are experienced in math. Take a look at this book http://focus.ti.com.cn/cn/lit/an/slod006b/slod006b.pdf Feel free to ask anyway if you have some problems
     
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  5. Georacer

    Moderator

    Nov 25, 2009
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    I don't see any other physical way to test this appart from actually using a signal generator and an oscilloscope. Both very expensive equipment, unless you 're lucky and have access to a laboratory's equipment.

    The simulation is a much more reliable method of theoretical study, though.
     
  6. sunone

    Thread Starter New Member

    Jan 11, 2011
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    Thank you for your reply.
    If you read my first question in the post, I am actually asking a specific question assuming that I have these instruments in my apartment and my lab:

    - Assuming I have a wave generator and an oscilloscope.
    - If I send to the input of the bandpass filter a square wave outside a the allowed frequency. What should I see if the circuit is working properly ?
    I assume nothing. If I see some micro-pseudo sinusoide is it still acceptable or this means I have done some mistake in the design? This is what I meant in the original question, sorry if it was not clear.

    Not really, I am sure you can find some cool and in good condition Tektronix even on Ebay :) :) for less than 1000 euro. Take a look :)
    About the wave generator, even the good one are no more than 100-300 Euro. And you can find also good stuff for less than 100 Euro, depending what you need.
     
    Last edited: Jan 17, 2011
  7. sunone

    Thread Starter New Member

    Jan 11, 2011
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