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Motion Sensor with LED's

Discussion in 'Electronic Basics' started by [email protected], Mar 5, 2007.

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  1. Guest


    Im having some difficulty trying to make a circuit.
    I want to create a desk lamp which only switches on/off when you wave
    your hand across the sensor.

    I will be using
    4x AAA batteries 1.5v Each 1150mAh
    8 LED 3.6 Forward Volts - 20mAh
    120 ohm Resistors

    Not sure about the sensor and other components..

    Please can someone help me specify the materials and circuit layout.

  2. There are at least five thick volumes of 'Encyclopedia of Electronics' or
    'Electronic Circuits' or some similar name. The author/collator or whatever
    has a short name which begins with G. I cannot remember any more detail but
    go to your local public library and have a search through the books on
    electronics. These will be the largest, fattest, books on the shelf. There
    are circuits for everything in those books.

  3. Guest

    You can use a simple infrared emitter diode and a photo-transistor
    like detector. You need modulate the signal if you don't want to have
    problems with other light/infrared sources like sunlight.

  4. me

    me Guest

    wrote in
    An excellent sensor for this application would be single pole single throw
    switch, as you wave your hand make contact with switch to turn on or off...
  5. Or the light from the lamp.
  6. hehe. Yes. But it might be a medical application where sterilized
    hands shouldn't make contact... In that case, I agree with modulation
    for the emitter and narrow-band filtering suggestions for the
    receiver. Must be ICs out there for this, already.

  7. Optical filtering would help, as well.

  8. Guest


  9. I can suggest some thoughts that were crossing my mind:

    (1) Ambient light striking the detector may present a significant
    level of current that is unrelated to the received signal. Reducing
    the level, by narrowing the angle of acceptance or filtering against
    wavelength or using polarization to advantage can aid design and
    robustness to varying ambient conditions.

    (2) Designing lenses for a narrow wavelength range may be easier, if
    they are used.

    Among others. There were more crossing my mind.

  10. Easy way would be to use the ir remote receiver module and place an IR led
    beside it ( pointing same direction ) running from a 40khz oscillator. The
    remote receiver module should have the light filter on it already. You will
    need also additional circuitry (flip flop and relay driver) to operate the
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