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Discussion in 'The Projects Forum' started by frdfreak, Sep 19, 2008.

  1. frdfreak

    Thread Starter Member

    Sep 19, 2008
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    I am trying to duplicate a circuit but cannot find the op amp. When i look it up in Mouser it comes back obsolete. I have zero knowledge about circuits orwhat low supplycurrent,gain-bandwidth product,and slew rate mean. I can purchace this cable for 32 but feel i can do it cheaper and learn something in the process [​IMG]. thanks frankie
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Hi Frankie,
    First, what is the part number of the op amp that you are looking for?

    Second, the image of the cable did not post properly. Could you perhaps post a link to the page the image is on instead?

    Thirdly, what does the cable have to do with the op amp?

    It will help us help you better if you can describe what it is you are trying to accomplish.
     
  3. frdfreak

    Thread Starter Member

    Sep 19, 2008
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    0
    the number is mouser #511-mc33171n
     
  4. frdfreak

    Thread Starter Member

    Sep 19, 2008
    10
    0
  5. Audioguru

    New Member

    Dec 20, 2007
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    Digikey has almost 2000 MC33171N opamps in stock for $1.09US each.
     
  6. SgtWookie

    Expert

    Jul 17, 2007
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  7. frdfreak

    Thread Starter Member

    Sep 19, 2008
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    the op amp is part of a pc/if adapter that connects radioshack scanner to pc. scanner is pro 95 trunkscanner picks up 800mhz police radios
     
  8. frdfreak

    Thread Starter Member

    Sep 19, 2008
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  9. hgmjr

    Moderator

    Jan 28, 2005
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  10. frdfreak

    Thread Starter Member

    Sep 19, 2008
    10
    0
    i typed in the part # and it came back obsolete not available but thanks i can get it through digikey
     
  11. DickCappels

    Moderator

    Aug 21, 2008
    2,664
    634
    In that circuit, the opamp is used as a comparator, connected as an inverting level shifter. Most single supply op amps that can run down to about 10 volts total power supply voltage and swing its output within a couple of volts of the V+ rail should work as long as the slew rate is fast enough to handle your data rate. Input offset should not even a concern in this application (guessing that the incoming signal is at least a few hundred millivolts P-P, and my gues its more like 5V P-P).

    Also from the datasheet, the slew rate of the original part is only 2 V/us. That's really slow, so just about anything will work as long as it meets the DC parmeters I mentioned above. The LM358 (dual) and LM324 (quad) are available everywhere and they are pretty cheap , and they should work just fine.
     
    Last edited: Sep 20, 2008
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