--- alan smith <micro_eng2@yahoo.com> wrote:

> This is more of a proactive question, because I am afraid I may have
> to come up with a better solution that whats currently being used.  I
> am being asked to come and evaluate an existing design where
> "stepping stones" are used to initiate a waterspray sequence.  In
> other words, as you step on particular "stones" it triggers a
> controller input.  
>    
>   Presently the sensing is done using a load sensor that sits
> underneath a fake stone so stepping on it causes an analog voltage to
> change and thus triggers.  I've been there once under contract to
> repair, where the load sensor took a voltage spike and had to replace
> (about 1K ea) it and also fix wiring issues, realign things, and
> basically re-engineer some of the control features.
>    
>   That was last year, and now I am getting a call from the end user
> (it was the design house that contracted me the first time) to come
> and look at it again.  Can you tell I'm excited about this?  So I am
> wondering....anyone have other ideas other than a load cell that
> would stand up to lousy enviormental conditions (being flooded,
> baked, froze, etc) and would keep working more than a year.  The
> "stepping stone" is attached to a plate that has the load cell
> attached to it, so whatever is done has to be easily retrofitted. 
> Cost isnt such an issue since its not a production run but a one-off
> deal.
> 
There is an old story "there are many ways to skin a cat" so if you
qualify what it is you need more precisely that might help.  "Load
Cells" can consist of anything from an semi driven piezo transducer
(this is often used in measuring scales) to stainless steel tranductor
(check out ABB for these) (measures strain inside a chunk of
stainless).  The latter being highly indestructible but not suited for
high temperatures, often these are used in steel rolling mills or just
rolling mills in general.  So you probably need to be more specific
about what the criteria are.  Actually you might answer your question
by doing so. :D

Stephen

Stephen R. Phillips was here
Please be advised what was said may be absolutely wrong, and hereby this disclaimer follows.  I reserve the right to be wrong and admit it in front of the entire world.


 
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