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shock detection

Discussion in 'Electronic Design' started by Michael, Nov 12, 2007.

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  1. Guest

    What? Something that can detect free-fall without external
    measurement?
    Just because you never worked with anything worth over 5$ doesn't mean
    it can't exist. Stop being so snide.
     
  2. Ecnerwal

    Ecnerwal Guest

    On further consideration, if I spent $25-40K on something "handheld",
    I'd expect the maker to have bothered to engineer it to take the normal
    things that can be expected to happen to a hand-held item, such as being
    dropped 3-8 ft onto a concrete or steel surface (in any orientation),
    without blinking, much less breaking. If it can't even be "bumped",
    you'd better sell it as a suitcase-sized item, with the package you have
    now sitting in the middle of a lot of soft foam, surrounded by a hard
    shell.
     
  3. Tim Williams

    Tim Williams Guest

    No, the gold does not. However, the owner of the toe beneath it does.

    Tales of Fort Knox eh...

    On topic: there are clear bouncy ball things with an LED flasher inside. A
    spring, clearly visible, bounces against a pin. A couple second one-shot
    is activated that runs the flasher.

    (Hmm, I wonder how they get the battery inside there. Rubber isn't cooked
    at a very cold temperature. Must be a different elastomer.)

    Any solenoidal spring always flexes easier in bending than in compression,
    and any axial force will soon end up converted to torsion and bending due
    to the spring's coiled geometry. Only one spring is necessary, but good
    luck calibrating it. It'll also have a resonant peaked response unless you
    immerse it in glycerin.

    Tim
     
  4. Nobody

    Nobody Guest

    How accurate does the timestamp need to be? Unless it needs to be accurate
    to the nearest second, you can just power up the system periodically to
    check whether the glass tube is still intact.

    This approach is commonly used for carbon monoxide detectors, which
    typically take one measurement every 30 seconds and run for 5 years on the
    supplied battery (which cannot be replaced, to ensure that the unit is
    replaced as a whole; the sensor has a limited lifespan).
     
  5. Jamie

    Jamie Guest

    but, i don't think that works unless it's powered up. The poster wants
    it to work even with the batteries out.
    That would imply a mechanical release snap switch which works with
    sudden stops how ever, the one's i've seen are not small because they
    need a little inertia to make it work.
     
  6. Jamie

    Jamie Guest

    what you need is a small "inertia switch" mounted on a small mini
    board or maybe part of your main board to be operating by a back up
    batter which maintains a low power pic or like that with a TOD clock in
    it that supports a calendar.

    inertia switches are very popular and are getting small.
    You could most likely construct a complete potted unit with a
    proprietary plug in device that only you would have the resources to
    connect to.
    I've seen this in medical devices so that only the manufacturer that
    made the equipment could connect up to it and down load information
    about service times and may other things that we don't want to know
    about. These devices normally have their own batteries in the potting of
    the device.
     
  7. John Larkin

    John Larkin Guest

    If we put him in a box, do you think he could tell if he was
    stationary, or falling?

    John
     
  8. Michael

    Michael Guest

    Ahah! This is interesting idea: use disposable detector and check it
    every once in a while. Thank you, I'll look into it...
     
  9. Tim Williams

    Tim Williams Guest

    Nah, put him in the box with a radiation-activated cyanide source. Then
    open the box and view his wavefunction.

    Tim
     
  10. The vomit comet is a good example. We know they are in free fall but to them
    they are in 0g. (Of course they know its free fall only by deduction)

    If you jumped out of a plane with your eyes closed and there was no
    atmosphere then you would not know your falling but you would think you are
    floating(exactly like the vomit comet... the plane itself acting to isolate
    you from the atmosphere) until you hit the ground.

    I don't mean that you cannot detect acceleration but simply that you cannot
    tell the difference between different "kinds". Although I suppose for
    practical considerations it doesn't matter much. A 24k solid gold handheld
    probably will never end up in the vomit comit. Also I seriously doubt that
    he's really interested in detecting "free fall" but impact(my guess is to
    void the warranty).

    Although, for example, if someone took the handheld on a plane its possible
    that it might detect "free fall" if it was not designed properly(or maybe
    that would need to be a dragster?).
     
  11. Jim Stewart

    Jim Stewart Guest

    I think you'd perceive it the other way - in
    weightlessness or jumping out of an aircraft
    without an atmosphere you'd think you were falling,
    at least until you were conditioned to the effect.

    We're well-programmed to expect 1 gee downwards
    all the time.
     
  12. mpm

    mpm Guest

    I don't know.?
    For the "abuse" part of this, you can probably arrange "lie-detection"
    services with a local company. If you suspect purposeful employee
    abuse, that alone might solve the problem (i.e., fear of losing one's
    job.)

    And would probably be cheaper and better in the long run.
    (Besides, you could ask other questions - like who's sleeping with
    whom, who's on drugs, who's stealing from the Company, stuff like
    that.)

    -mpm
     
  13. John Larkin

    John Larkin Guest

    Except on Monday mornings, when it's 1.8.

    John
     
  14. Ross Herbert

    Ross Herbert Guest


    You need Shockwatch
    http://www.shockwatch.com/pdfs/SWCL1-06_s_and_h_monitors.pdf
     
  15. neon

    neon

    1,325
    0
    Oct 21, 2006
    the best place is the USA goverment for A SOURCE of their tests. There is E.M.I, SHOCK, VIBRATION, SPEED, TEMPERATURE, ALTITUDE, HIPOT, DROP AND FINALY TEMPEST. THEY DO IT ALL.
     
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