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  • Re: timers

    Dear Dong,

    I was interested to read your reply. Especially with regard to the
    cost of the project. I have made timers based on a 555 IC, a few
    latches (flip/flops), logic gates and a counter for a price of around
    $20. There is really no limit to the potential number of triggers
    (processed with a few logic gates) so I can't see why you'd ever need
    to spend more.

    David Bastians
    Lecturer
    School of Community Health: Physiotherapy
    Charles Sturt University
    Box 789
    ALBURY 2640
    ph02) 6051 6739, fax02) 6051 6727
    mailto:dbastians@csu.edu.au


    > -----Original Message-----
    > From: Biomechanics and Movement Science listserver
    > [mailto:BIOMCH-L@NIC.SURFNET.NL]On Behalf Of Dong CHEN
    > Sent: Monday, 9 October 2000 10:21
    > To: BIOMCH-L@NIC.SURFNET.NL
    > Subject: Re: timers
    >
    >
    > Dear Jeff,
    >
    > I developed a timer used to control the signal output one
    > year ago. This
    > small timer system can be controlled both manually and
    > electronically. The
    > basic idea of this timer development is to use a Monostable/Astable
    > Multivibrator (CD4047) to generate a basic clock frequency;
    > and use several
    > Decade Counters/Dividers (CD4017) to get the timing accuracy
    > you want. All
    > manual or electric control, and input or output of the timer
    > can be built
    > up based on this basic structure of the timer. The cost (not
    > include the
    > labor) should be within $400USD.
    >
    > Also, it might be possible to use some kind of software
    > package (LabView)
    > combining with other I/O device to realise the function you
    > need if you
    > have these facilities. But, I have no experience of this approach.
    >
    > This info is just for your reference. Please don't hesitate
    > to contact me
    > if I could be of any further help.
    >
    > Cheers,
    >
    > Dong
    >
    >
    > At 10:29 6/10/00 -0500, you wrote:
    > >Biomech'ers
    > >We are looking for simple digital timers/stopwatches that
    > >can be controlled electronically or manually. For example, an
    > >external electronic circuit with a manual switch or TTL signal
    should
    > >be able to stop and start the timer. We would also like to
    > at some point
    > >be able to hook up photoelectonic switches. These timers will
    > >be used for reaction time and movement time studies as well as to
    > >double check some of our timing data we gather from our kinematic
    > >and kinetic instrumentation.
    > >
    > >The timer needs at least 1 ms precision and readouts. Layfayette
    > >Instruments has such devices, but they are expensive (about
    $600USD).
    > >It seems to me that less expensive devices are available. I am not
    > >against building a timer, as long as I can get the parts off
    > the shelf
    > >(e.g. RadioShack) and have easy instructions.
    > >
    > >Anyone have any suggestions?
    > >--
    > >Jeff Ives, Ph.D.
    > >Dept. of Exercise & Sport Sciences Phone: 607-274-1751
    > >Ithaca College Fax: 607-274-1943
    > >Ithaca, NY 14850 USA Email: jives@ithaca.edu
    > >
    > >---------------------------------------------------------------
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    > >For information and archives: http://isb.ri.ccf.org/biomch-l
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    > >
    > >
    > //////////////////////////////////////////////////////
    > Dong CHEN
    > PhD, MEng, BEng
    >
    > School of Physiotherapy
    > Faculty of Health Sciences
    > La Trobe University
    > Bundoora, VIC 3082, AUSTRALIA
    >
    > Tel: +61 3 9479 5771; FAX: +61 3 9479 5768
    > http://www.health.latrobe.edu.au/Health/Schools/PT/
    > /////////////////////////////////////////////////////
    >
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