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Thread: op amps to amplify signal? EE majors needed

  1. #1
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    op amps to amplify signal? EE majors needed

    ok.. heres my delimma..

    i have my computer that has a soundblaster audigy hooked up to a my pioneer deh-940mp cd player through the aux in.

    the problem comes that i have to turn the volume up to about 30/40 to get the same loudness from the mp3's from the car computer than i would if i just put the mp3's on a cd and played it internally on the cd player at around 20.

    so my solution was maybe using the opamp circuits found in those tin can headphone amplifiers to amplify the signal output between the soundcard and the aux inm But modifieng it to use a 12V from my opus.

    would that work?

    heres the site that has the schematics for the headphone amp

    http://headwize.com/projects/showfil...=cmoy2_prj.htm

    http://tangentsoft.net/audio/cmoy-tu...angent-sch.pdf
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  2. #2
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    You're on the right track. Sounds like you need a small pre-amp. But you'll have to build a stereo version to handle left and right audio channels. There are a few IC out that will handle both in the same package.

  3. #3
    Maximum Bitrate kiltjim's Avatar
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    I agree. And KE4NYV is right, there are dual opamps out there with very similar setups. You just have to find the right one. The only part number that is coming to mind is the 741, but its been a while since I worked with opamps.
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  4. #4
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    Sounds like a pretty easy (and worthwhile) job. I found the dual amplifier version of the same opamp from the first project on DigiKey: OPA2134PA-ND

    They're only about $2 each so that's pretty cool... especially since you can order the rest of your parts there too and keep it WAY cheaper than RadioShack (like the DIY suggests).

    Good luck!

  5. #5
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    Quote Originally Posted by LegoGT
    Sounds like a pretty easy (and worthwhile) job. I found the dual amplifier version of the same opamp from the first project on DigiKey: OPA2134PA-ND

    They're only about $2 each so that's pretty cool... especially since you can order the rest of your parts there too and keep it WAY cheaper than RadioShack (like the DIY suggests).

    Good luck!

    dammit... im such an idiot...

    i ordered that opa2134 opamp just after i posted... (it was a couple of bucks) and it never occurred to me to order hte rest of the stuff from there while i was ordering.. i just figured ill go to ratshack and pick it up.

    sometimes my stupidity amazes me
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  6. #6
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    Quote Originally Posted by kiltjim
    The only part number that is coming to mind is the 741, but its been a while since I worked with opamps.
    Like what, 40 years?
    I have found you an argument; I am not obliged to find you an understanding.

  7. #7
    Newbie canopy's Avatar
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    Quote Originally Posted by kiltjim
    I agree. And KE4NYV is right, there are dual opamps out there with very similar setups. You just have to find the right one. The only part number that is coming to mind is the 741, but its been a while since I worked with opamps.
    741? Damn! Thats like the first one used when I was learning electronics...

    Go to the philips semiconductor page and search for the TDA.... Ic's, I'm sure you'll find something that suits you...

  8. #8
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    School still uses 741s, nothing wrong with that. School kids only gonna blow them up anyway so why use expensive hard to get parts.

    Of course for serious audio preamps dont use 741s because there are plenty out there these days, alot better, newer design.

  9. #9
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    I would be inclined to capacitively couple the input and outputs if I dont really
    know the innards of what I am connecting to. No potential offset issues etc.
    741? lets at least advance to til072
    cmoy's all good.

  10. #10
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    I'd suggest using the NE5532, very common op-amp, used in the best audio applications
    http://www.fairchildsemi.com/ds/NE%2FNE5532.pdf

    Some circuits...
    http://www.geocities.com/ferocious_1999/md/juanmi.htm
    http://sound.westhost.com/project30a.htm

    Cheers,

    Niall

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