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Thread: 741 Op-amp wiring help please?! :)

  1. #21
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    Get rid of the 5.1K resister, and while you're at it use a better op-amp!
    Ok, we've been there with the 741!! It seems to be working ok and i only ever scan up to 15k, whats the problem?

    Why is the 5k1 resistor not needed? What is it supposed to be doing in the circuit?

  2. #22
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    Quote Originally Posted by norty303 View Post
    Ok, we've been there with the 741!! It seems to be working ok and i only ever scan up to 15k, whats the problem?

    Why is the 5k1 resistor not needed? What is it supposed to be doing in the circuit?
    I don't know about the 5.1K resister. I think that might be an attempt to create a balanced impedance output. Perhaps this design assumed that you had no way to get -12VDC to go with the +12VDC. I think if you use pin 3 as a signal ground you will get your correct center of zero volts, relative to the +12 and the (isolated) GND.

    I wouldn't do it like that. You have both +12 & -12 volts!

    James.

  3. #23
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    Thanks so much James, I took the plunge anyway, snipped off the resistor, added the extra wire and fired it up......

    BINGO!!

    Would've posted back sooner but I've been watching some laser shows!


    Will try and post some pics and videos from the weekend as reward, coz i hear you lot like that sort of thing....

  4. #24
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    You should apply your new found knowledge of op-amps and make a sound card DAC with The LaserBoy Correction Amp!

    James.

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