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Turn 12v engine on/off from a PC

Discussion in 'Electronic Basics' started by Luis, Oct 23, 2003.

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  1. Luis

    Luis Guest

    I need to turn a 12V engine on and off from a computer program running
    in a PC and at the same time use a set of IR emitter and receiver to
    know to know if a sheet of paper is between the two.
    Can someone suggest a part list and schematic including the wiring to
    a standard port (serial, parallel or USB).
    Pointers to similar projects are welcome.

    The engine control and the sensor are independent, the program running
    in the PC will provide have all the logic.
    I have a very basic knowledge of electronics but I know how to
    read/write to the PC ports.

    Thanks in advance
  2. Lord Garth

    Lord Garth Guest

    You could open and old mouse and use its optical interrupters and
    interface circuitry for your slot sensor. As for the 12 volt motor,
    what sort of current does it require?
  3. I hacked this up for you:

    You'll trash your PC with huge inductive spikes. Use optoisolators only.

    In addition, I used an OPB680 rather than a normal slot interrupter because
    IR can apparently see through some kinds of paper. You might not want that.
    The OPB680 has a little plastic door that can get pushed by a piece of paper
    without bending the paper. Using something else should work, just check the
    current requirements.

    If you could post your program on how to control the parallel port (on
    alt.binaries.schematics.electronic please) I'd be indebted. Pesky Windows
    PCs aren't nearly as friendly to program as a nice MIPS core... no branch
    delay slot? You gotta be kidding...

    Or you could email it to me at rcmonsen hat comcast dot net.

    Bob Monsen
  4. Luis

    Luis Guest

    I have open my mouse and realized the paper is transparent to IR, I
    only got a reaction in the mouse pointer when I use plastic or metal.
    Do you know how can I tune the sensibility of the interruptor?

    I was going to use a cheap ac-adapter with 12v motor I have somewhere.
    But because I will use a very slow gear I'm also considering using a
    3v walkman motor.(the paper sheets are small and thin)

    thanks again.
  5. Lord Garth

    Lord Garth Guest

    You might need to reduce the current to the Ir emitter using a resistor.
    I can't tell you the value, you'll just need to experiment. The reduced
    intensity may do the trick but if not, you may need to build your own
    using a visible LED and a photo transistor. Very likely you can remove
    the optical interupter from the mouse and bring the connections out a short
    distance to accomplish this.

    As for the motor, you state the voltage, I wanted to know the current but
    I suspect a common transistor ought to do.

    What is it you are attempting?
  6. Luis

    Luis Guest

    Thanks you very much for the schematics, that's what I need!
    Do you think I can keep a 100% optical interrupter if I manage to tune
    the phototransistor sensivity and/or filter the LED light?

    I will send you my source code when I get it working.
    Meanwhile I can sugest you the folowing programming resources(high
    level languages)

  7. I don't know. I'd probably go with the little plastic window, but who knows?
    You don't have much to lose by trying it.

    Also, look at the schematic again. I just deleted ground connections where
    there should not have been any... remember, no connections of any kind
    between motor and PC. They were there for simulation purposes.
    Thanks, I'll look them over.

    Bob Monsen
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