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How to simulate an IR Emitter & Detector?

Discussion in 'Electronic Design' started by [email protected], Jan 28, 2005.

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  1. Guest


    I am simulating a Magnetic levitation circuit in Multisim and I am
    having problems simulating the IR Emitter and Detector. How do I
    simulate the varying resistance of the circuit depending on the
    position of the levitated object?

    Any suggestions of doing this in Multisim or any other package will be
    much appreciated.

  2. Rich Grise

    Rich Grise Guest

    Get a physical LED, and physical photodiode or phototransistor (i.e., your
    detector), a power supply, a multimeter, and a piece of cardboard, and
    _measure_ the silly thing!

    Doesn't anybody do anything _real_ any more?

    Good Luck!
  3. not since the group Weller died (msg :Weller WTCPN Problems)


    Serious error.
    All shortcuts have disappeared.
    Screen. Mind. Both are blank.
  4. Naa,
    the solder iron is too heavy, there are too many dials on
    a scope and there comes real electricvty out of a power
    supply. And the investment ...

  5. Mark Jones

    Mark Jones Guest

    I think he wants to learn how to simulate the effects of the maglev
    feedback sensor in software, not just get an answer.

    Sounds tricky.

    If your simulation software will let you build "devices" out of SPICE
    primitives (VCVS, ICRS, etc,) then this is the way to go. Think of the
    problem not in terms of volts and amps but how the different aspects
    of the desired movement reflect changes in the circuit output, then
    design a schematic to do just that. You'll need to setup the IR in
    prototype anyways, to verify your results (no such thing as a free
    lunch.) Have fun.
  6. Thanks Mark,

    That's exactly the point. I already have the physical setup and was
    trying to do a simulation of the same for future modifications to the

    Thanks for the tip.
  7. James Meyer

    James Meyer Guest

    Just curious... How are you simulating the inertia of the suspended

  8. Rich Grise

    Rich Grise Guest

    Yeah. What's the transfer function of a lump of metal hanging from a
    solenoid, with optical position feedback? ;-)

  9. Rich Grise

    Rich Grise Guest

    Thinking of a weight, hanging there by a magnetic field, that's controlled
    on a time scale probably much shorter than the time constant of the
    solenoid, where the farther away it gets, the less pull there is....

    Got it!

    Negative Inductance!

    (in parallel, of course, with imaginary capacitance.)

  10. I read in that Rich Grise <>
    Any such system can be modelled electrically. We do it all the time with
    loudspeakers and microphones. Both the acoustic and the mechanical parts
    of the transducers can be modelled as RLC circuits.
  11. Rich Grise

    Rich Grise Guest

    So, naturally, determining those component values is left as an exercise
    for the reader, right? ;-)

  12. I read in that Rich Grise <>
    No. There are scaling factors involved which are specific to the problem
    to be solved, so there are no simple general formulae. There are many
    textbooks that treat the subject in depth, such as 'Dynamical Analogies'
    by Michael Gayford.
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