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Thread: ADAT mods +/-5v instead of 10v

  1. #11
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    Surprised I donít know you. Maybe I do? Did you have a bird by chance

  2. #12
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    A bird? Not sure what you mean. I had a pair of cockatiels for awhile? But very few people knew that.

  3. #13
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    Quote Originally Posted by Theoneinformant View Post
    But I cannot figure out how to properly limit the output of the x-y channels to +/- 5v.
    The output from the blackface is 0-10 volts single-ended, right? In that case you need to build a differential receiver with gain adjustment and zeiners on the outputs to prevent over-volting. I've got a schematic at home I can post later tonight. Or am I missing something here?

    Adam

  4. #14
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    Output from a blackface is 10v diff

  5. #15
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    Quote Originally Posted by Theoneinformant View Post
    Output from a blackface is 10v diff
    Got it.

    OK, this circuit will work with a slight modification. You'll need to change the feedback resistor on the first op-amp from 10K to 5K. (Feedback resistor connects the output of the op amp to the inverting input. It's the vertically-oriented resistor below the first op amp.) That will cut the gain of the receiver stage in half. From there on everything should work correctly.

    X and Y buffer circuit.bmp

    If you don't change that first feedback resistor the output of the receiver stage will clip when it reaches the max input voltage. You *could* run this circuit as drawn if you go up on the power supply voltage to the op amps (something like +/- 24 volts ought to do it), but then you'd have to dial the size pot way down to prevent the zeiners on the output stage from clipping the image.

    Adam

  6. #16
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    Good idea, but I am trying to figure out what resistor value to change in the op amp inside of the adat. I have the value for the + side. Haven't worked out the - side yet. Got stuck on other parts of the project, moved the whole projector onto a different breadboard, and I'm working on a high power long distance corrected nubm44 diode build. Long distance = 32000 feet, or 7.25 miles. Divergence is down to the point I'm having a hard time measuring it over 100yds.... Once I have that one worked out in going to pbs it with a second nubm44...

  7. #17
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    You might look at the drv134 series of drivers send the signal down the line differential. You can then increase the voltage of the signal to compensate for the line loss. 7 miles of copper is a crazy cost. Can you do an rf solution or even an optical solution if line of sight?

  8. #18
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    I'm trying to get the diode to be a visible spot at 7 miles. The nubm44 diode is a 7w capable diode, not send the signals that far.

  9. #19
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    GO LED. You get much better power and the divergence is actually good unless you want super secret communication. In the case encode the transmission. There is a study regarding the mode hoping of laser vs led and led wins. You use a fresnel lens system. 7 miles is really simple. The ones i was looking at were doing 62miles.

    http://www.lightwaveonline.com/artic...-53449272.html
    http://modulatedlight.org/optical_co...cal_index.html


    as an example. Matt was actually the one that pointed me to led when I tried what you are doing.

  10. #20
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    I'm looking for spot on target, it's not for communication.

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