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Swimmer block departure time

Discussion in 'Electronic Basics' started by Douglas, Jan 19, 2005.

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  1. Douglas

    Douglas Guest

    First, I'd like you to know that I'm a novice.

    I want to record the moment that a competitive swimmer leaves a
    starting block, i.e. the instant the toes leave the block. As a basis
    of this, I'm thinking of using a piezo electric device, clamping this
    between the block and the pool deck, and recording the change of
    voltage.

    An alternative idea is to use a light beam (laser) that would broken
    while the toes are on the block, and made when the toes just left the
    block.

    Do you think any of these sounds like a reasonable way to proceed?

    Thank you,

    Douglas
     
  2. Yes, sounds reasonable. Here is a link I found:

    http://www.media.mit.edu/resenv/classes/MAS836/Readings/MSI-techman.pdf

    Also, conductive foam can be used as a pressure sensor, since it's
    resistance varies according to pressure. This could be a cheaper way to go.

    http://www.inventables.com/i/itemview_shared.asp?ItemID=667

    (I had to give my email to see the link above, so they may be soliciting
    for leads.)

    The laser thing would be hard to control, I think.

    Don't swimmers just go on the gun? You can easily measure a sound as
    loud as a gun, and use it to start a clock.

    How will you measure the end of the lap? That seems a bit more difficult.

    --
    Regards,
    Robert Monsen

    "Your Highness, I have no need of this hypothesis."
    - Pierre Laplace (1749-1827), to Napoleon,
    on why his works on celestial mechanics make no mention of God.
     
  3. This would be good for recording the delay from starting gun
    to launching effort. The toes off point would less distinct.

    I would think you want to record also the starting gun sound.
    Maybe an embedded microphone would do both jobs. I
    expect that pushing off generates detectable noise and that
    relative quiet would mark the toes gone condition.
    Ordinary LED light would do. A simple circuit with one
    NPN transistor, one NE567 tone decoder, and an op-amp
    will make a sensitive thru-beam detector that would continue
    to work right with water on the transmitter or receiver.
    Yes, more or less.
    You are welcome.
     
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