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Thread: DC offset circuit schematic wanted

  1. #1
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    Default DC offset circuit schematic wanted

    Anyone have a circuit to put and offset on a signal.

    Looking to add add quick pot adjustment inline with my projector so I don't have to goto my UGC for offset touch up. The one UGC is card based with just trim pots and there enclosed.

    Thanks
    leading in trailing technology

  2. #2
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    Smile

    Assuming you are talking about single-ended (that is, referenced to ground) signals, you want a summing amplifier.

    This page has an easy-to-follow example. Scroll down to the middle of the page.

    Any op-amp will work. The TL-082/-084 would be idea.

    If you're playing around with X and Y signals though, that is differential signalling (referenced to each other, X+ and X-, and not to ground). So you need a differential receiver on the front end to convert the signal to single-ended, then you'll have the summing stage (the output of which will be X+), and finally you'll need an inverting back-end on the output of the second op-amp to give you the X-. So 3 op amps instead of just 1.

    Adam
    Last edited by buffo; 08-31-2015 at 07:39.

  3. #3
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    Quote Originally Posted by buffo View Post
    Assuming you are talking about single-ended (that is, referenced to ground) signals, you want a summing amplifier.

    This page has an easy-to-follow example. Scroll down to the middle of the page.

    Any op-amp will work. The TL-082/-084 would be idea.

    If you're playing around with X and Y signals though, that is differential signalling (referenced to each other, X+ and X-, and not to ground). So you need a differential receiver on the front end to convert the signal to single-ended, then you'll have the summing stage (the output of which will be X+), and finally you'll need an inverting back-end on the output of the second op-amp to give you the X-. So 3 op amps instead of just 1.

    Adam
    thanks...............
    leading in trailing technology

  4. #4
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    See attached... This is not licensed for production... For those who know something about the ILDA standard circuits, note I flipped the output lines for to compensate for the inverting summing amp. This design has a glitch in that you can saturate your galvos to one side with a collapsed image with too much offset.
    Increase the 4.7K Ohm resistors as needed to prevent this effect. My real unit has the scaling circuit configured so that the image size can go from minus two to plus two on one potentiometer, so I have flip-flop and can amplify ADATS... But this will get you started.

    Meet my little friend, the "Universoul Scalizer"

    Steve
    Attached Thumbnails Attached Thumbnails UniversoulScale.png  

    Last edited by mixedgas; 09-01-2015 at 10:31. Reason: corrected clamp circuit
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