Re: Sat on a Toilet Sensor ?

["Karam Karam" <kzkaram@xxxxxxxxxxx>]

Marcus,

Infact we know of a customer who has used a piezo-resistive material=20
to detect the load change. This goes into one of our analogue modules=20
and the signal change gets used to detect seating/unseating. In this=20
case the sensing method is suitable because the rest of the=20
automation infrastructure and sufficient signal filtering capability=20
is already in place, ie. the messy signal from a cheap sensor can be=20
easily integrated to actions (flushing toilet on unseatng in this=20
case but could also be fan on seating - I daren't suggest what other=20
possibilities exist ;-) ).

In your case where you want just a localised solution, it may be that=20
an integrated IR sensor might do the job such as the Sharp GP2D12 (do=20
a search for this part number on the Farnell web site and you should=20
see one or two variants @ around =A312). These use a triangulation=20
pronciple so should be more accurate than ultrasound. I think the=20
digital ones give a logic signal output which with a little bit of=20
extra electronics should be good enough to drive a relay though you=20
might need a bit of logic in between eg. perhaps a timer to 'smooth=20
out' the signal (ie. keep fan running for a while even after=20
momentary loss of detection) but this you might tell better after=20
experimentation with such a device.

Karam
IDRATEK LTD



--- In ukha_d@xxxxxxx, "Marcus Warrington"=20
<marcus.warrington@...> wrote:
>
> OK.. I need some ideas for a little problem I have.
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> I am currently refitting our bathroom and I need a way of=20
activating a
> fan but ONLY when some is SAT on the toilet. The fan is a "pan
fan"=20
that
> extracts air from the toilet bowel to prevent.. err.. smells..=20
pervading
> the room. I did a mini bulk buy of these a few years ago.. which=20
reminds
> me, Kevin.. I still have yours in a box somewhere.. let me know your
> address and I'll get them sent to you!
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> My first thought was a PIR but that would be difficult to restrict=20
to
> only "sitting" on the toilet i.e. it would detect if someone
reached
> down and lifted up the seat , or maybe even some one standing there=20
to
> pee etc.
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> Next thought was use an ultrasonic sensor mounted on the wall=20
behind the
> toilet bowel (the cistern is concealed in the wall) and adjusted to
> point down at a 45 degree angle so that it covered the rear half of=20
the
> toilet. Problem is I'm not too sure how "focused" the beam
can be=20
made
> on these devices.
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> Another thought was to use a stress sensor (or weight sensor ?) on=20
the
> toilet bowel. In some ways this would be the ideal since it would=20
not
> rely on proximity to trigger. Problem is I have no idea what I'm=20
looking
> for, how much they are, how easy they are to integrate with a relay=20
etc
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> Anyone got any ideas ?
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> Marcus
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> [Non-text portions of this message have been removed]
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