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Thread: Ideal sound card for multichannel scan and modulations.

  1. #101
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    OK. You've got +5 volts. Now what?

    James.

  2. #102
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    Then add a HF inverting power supply and use rail-rail op amps.

  3. #103
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    Yea, there are ICs that are specifically to convert from single ended to balanced. I think I may have even seen them on here... maybe in the schematic for the USB DAC the guy posted awhile back.

    PCI is nice but USB is the way to go since most people will want to use it with a laptop to be portable. But, if you can put it in one of those little laptop PC cards you get extra points. haha.

    It would be nice to have it powered by the USB power... how would that work? My Moncha DAC is powered by USB and has balanced outputs so I know it's possible. On board DC-DC converter?

    Sounds like a cool project! Unfortunately I am stupid when it comes to electronics design so I can only make requests. LOL.

    But, on the other hand... if going to all that trouble why not just design a USB DAC that natively takes laser frames. I don't think it would cost any more and you would have more flexibility to add advanced features to the firmware. So, maybe it only makes sense to make the amp section instead of a full blown device afterall.

  4. #104
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    Is it really all that crazy to think about PCMCIA?

    Or is that already dead?

    I guess it's not that hard to make a differential PS. The one I use to drive my op-amp 24dB/oct. active crossover for my living room bi-amp system fits in the palm of my hand and was made from parts of a blown up computer PS.

    Two wall warts in a box will do!

    I know! All we need is a PCMCIA card or PCexpress card blank to get the +/- 12 VDC.

    James.

  5. #105
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    I think USB powered is the way to go. With PCMCIA/Expresscard you need some kind of an adapter to put it in your stationary PC, but USB works on any computer as it is.

    Now, as for the lack of a negative voltage there are nice DC-DC converters that do the job for you. Only problem is that they're pretty expensive. Here a +5V to +/-12V SMD converter costs $13.

  6. #106
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    "Here a +5V to +/-12V SMD converter costs $13."

    That sounds ideal!

    I guess you don't really need much current, but what can this do?

    James.

  7. #107
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    The +/-12V model can do 40mA; should be enough. Check out the datasheet here:
    http://www.elfa.se/pdf/69/06901169.pdf

    I think it's really neat to have everything integrated into a nice SOIC 18 package.

    Can anyone find a better price on these?

  8. #108
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    Quote Originally Posted by tocket View Post
    Here a +5V to +/-12V SMD converter costs $13.
    That's because it's in a package already built. You guys saw my post about using a 5V inverter and rail-rail amps a bit back, right? That inverter-converter would cost 4x less, and be more efficient at the same time.

  9. #109
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    Do you think it is wise to be right on +/- 5VDC?
    Don't you like a little wiggle room for tuning and stuff?
    Seems like it would clip easy; OK for colors, but not for galvos.

    Please point out your post!

    James.
    Last edited by James Lehman; 06-11-2008 at 17:23.

  10. #110
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    Quote Originally Posted by James Lehman View Post
    Do you think it is wise to be right on +/- 5VDC?
    Don't you like a little wiggle room for tuning and stuff?
    Seems like it would clip easy; OK for colors, but not for galvos.

    Please point out your post!

    James.
    "Then add a HF inverting power supply and use rail-rail op amps."

    It would clip only if the gain were set too high. So, at max maybe we're feeding the galvos 4.95V peak instead of 5.00V, seems like a good tradeoff to me.

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