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Dong Chen
10-12-2000, 05:08 PM
Dear David,

After reading Jeff's summary of the timers, I would like to have the
further comment on your question of the cost of the timer development.

The main difference between your $20 and my $400 is that your cost is based
on the component cost only, and my estimation is the "development cost"
which also includes the cost of accessories and PCB layout. Also, my
estimation includes the possible signal input and output processing in the
system development, which is not included in your consideration.


Thanks,

Dong



At 11:32 10/10/00 +1000, you wrote:
>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
>ph:(02) 6051 6739, fax:(02) 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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>> >---------------------------------------------------------------
>> >
>> >
>> //////////////////////////////////////////////////////
>> 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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>
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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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