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clocking start and stop times for runners

Discussion in 'Electronic Basics' started by DaveK, Jul 23, 2007.

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  1. DaveK

    DaveK Guest

    I NEED HELP! I WOULD LIKE A CIRCUIT TO RECORD A RUNNER'S TIME.


    The times would not necessarily have to be accurate, but consistent to
    some degree. This information would be used to evaluate my son's
    speed and in-turn, use this information to see if any certain
    improvement in his running technique or training regiment would make
    any difference in his times. Nothing has to be fancy. I could rig up
    any type of fixture to line up any sensor that may work with this kind
    of application. Below are some suggestions/questions which I don't
    have a clue would even apply.


    1. Would starting the clock (switch button & the word go) and some
    sort of sensor to stop the clock work? Better yet, a sensor for the
    player to break a beam to start and stop the clock. This would take
    out the difference in time from a runner's hesitation.

    2. What about infrared sensor?

    3. If the runner were to run in a low-light setting, could a
    phototransistor and an incandescent bulb be used?

    4. Are any circuits available in other devices such as clocks,
    appliances, etc., that could be used in conjunction to limit labor,
    parts or cost?

    5. Is this even doable? I have a fair amount of knowledge with
    electronics and component, but need a lot of help.


    Any suggestions would be greatly appreciated.
    Dave K
     
  2. Rich Webb

    Rich Webb Guest

    [snip...snip...]
    Reaction time is a factor in this. I'd use a microcontroller to fire a
    piezoelectric beeper at the start (what do the real track and field
    guys use, something like beep-beep pause beep-beep pause beeeeeeeeep?)
    A laser pointer to photo-transistor to trigger the stop. A modulated
    laser would have more immunity to false signals but if the receiver
    was in a shielded tube (paper towel tube, painted flat black on the
    inside) you could probably use a CW gizmo.

    Radio Shack should still carry "logic level" beepers (built-in driver)
    and the photo-transistors. IIRC, their peak sensitivity is IR but a
    red laser pointer may be enough to turn one on.
    Narrow beam flashlight would probably do it, too.
    Something like a Basic Stamp (www.parallax.com) would do the trick if
    you don't have a drawer full of assorted microcontrollers.
    Should be easy if the start and finish are reasonably close. If
    they're 26 miles and change apart, Hmmm ... have a cell phone on
    speaker set up at the start site to broadcast the starting beeps?
     
  3. Lord Garth

    Lord Garth Guest

    You neglected to say the limits of the timer. I would guess less than
    one hour should do.

    Are you okay with purchasing a timer or do you prefer to build the device?

    The photogate should always be a modulated light source so that external
    interference can be filtered out. This being the case, an incandescent lamp
    would
    be a poor choice.

    An Ir sensor detects over too broad of an angle so this too is a poor
    choice.
    If you remove the fresnel lens, the detection angle would be narrower but it
    is still a passive sensor, meaning it would detect any heat source.
     
  4. DaveK

    DaveK Guest

    Thank you for getting back to me.
    Yes, I am ok with purchasing a timer, but I am not sure how this would
    tie in. I not to smart!!
    Is there any other divice or sensor that may work for the stoping and
    starting the clock besides a manual push off and on swith.
    The distance is 40yrd. (40yrd Dash)
    Can it be accomplished without the use of a microcontroller?
     
  5. Lord Garth

    Lord Garth Guest

    By purchasing a timer, you eliminate any need to build with a
    microprocessor.
    You will need to find a timer, cooking timers usually count down rather than
    up,
    that you can hack. You will need to be able to solder wires to the timer
    trigger.

    An optical gate will require electronic construction skills. A likely
    circuit will include
    a 555 timer IC to create a pulsing light beam for the transmitter and
    another to
    create a missing pulse detector for the receiver.

    Perhaps the easiest approach is to get the optical beam sensors used on
    garage
    doors. Though this isn't the least expensive plus the operating voltage
    might not
    be DC.

    I once found an all in one unit that used a mirror at the opposite side and
    provided
    a relay closure for the output. This you would normally connect to a bell
    to sense
    people crossing some area. I'd tell you the name but it is installed at an
    office a
    few miles from here. Perhaps I can go there this week and write further.
     
  6. Guest

    i want the design for a timer with a pulse delay of 1min and 1 usec
    at freq 1 Mhz
     
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