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Thread: 15kpps scanner signal, what are the values?

  1. #1
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    Default 15kpps scanner signal, what are the values?

    I have a generic laser galvo scanner. I would like to know what voltage i need to feed to it to control its rotation manually.

  2. #2
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    +-5V is what they take.

  3. #3
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    Thnaks, does this mean 0 to 10V can be used or no?

  4. #4
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    Quote Originally Posted by piydadorto View Post
    Thnaks, does this mean 0 to 10V can be used or no?
    No, I don't think you can do that. You would just connect from most DACs gnd (pin 1 i think) to X+ or Y+. Leave X- and Y- unconnected to the scanner.

  5. #5
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    I dont want to connect it to a DAC but a microcontroller which can output 0-5V analog signal. This is what i meant by controlling it manually. I can amp it up to 0-10V but dont know how to convert that to -5 - +5. Any ideas?

  6. #6
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    You need a correction amp of some sort but I am not sure of the best way to do that. Brute force you could use an opamp but I have to imagine there are more modern ways.

  7. #7
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    Here's a basic circuit to convert 0-5V to +/-5V. The opamp can be just about anything. Rail-to-rail types will need a supply voltage of at least +/-5V, crusty things like TL0x series will be happiest if supplied something like +/-9V. The resistor values aren't critical as long as they're the same.

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    As an alternative, if your drivers have differential inputs, you can connect your 0-5V signal to the positive input and connect the negative input to a constant +2.5V. The driver will then see effectively a +/-2.5V signal. Likewise if you have a 0-10V signal, you would connect the negative input to a constant +5V.

  8. #8
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    Hey thanks. Much appreciated, , looks simple enough.
    That said I don't have a +-5V PSU. Any chance a +-12V PSU can be used? Maybe even the one powering the scanner drivers?

  9. #9
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    Sure, as long as the op amp is spec'ed for +/-12V operation--and that gives you enough headroom for TL07/8x parts which are pretty common.

    Just to be clear, though, the +5V reference in that schematic still has to be +5V regardless of what your supply voltage is. You can derive a 5V supply from the 12V supply using a simple 7805 regulator. You might want to add a load resistor to the 7805's output for stability, maybe something like 500R.

  10. #10
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    Neat. Thank you, didn't expect to get away so easily.

    Well I kind of didn't, just realised Arduino's analog out is only 8 bit, will need to find a better mincrocontroller.

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