RE: Sat on a Toilet Sensor ?

["Marcus Warrington" <marcus.warrington@xxxxxxxxxx>]

Tim,



Yes, strain gauges where what I was thinking off. But no idea what type
or specification I would need. The Toilet is bolted to a metal support
frame behind the panel so I guess this would be where I mounted the
strain gauge.



The PIR beam is a non starter because there is no wall or convenient
mounting position on either side of the toilet...



Marcus

________________________________

From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf
Of Tim Hawes
Sent: 11 July 2007 12:05
To: ukha_d@xxxxxxx
Subject: Re: [ukha_d] Sat on a Toilet Sensor ?



I think what you need is a "strain" gauge... (snigger) ;-)
Seriously though, perhaps a better term would be "load cell".

As an alternative, Ian modified a Maplin beam break sensor to indicate
traffic through a doorway (IIRC), maybe you could mount one firing
across the toilet seat and include a timer so it only activates the
fan if the beam is blocked for 10seconds say, to avoid false triggers
due to the seat being lifted etc.
Also IIRC, there's some details on his site at: www.mollyology.com

There's a lot of this beam-break stuff used on industrial machinery as
interlocks instead of physical guard rails/barriers. RS
(http://rswww.com <http://rswww.com> ) has a
selection, but at
industrial prices :-(

One final off-the-wall suggestion, put an electrode on each side of
the toilet seat, when the person sits down they make the circuit and
you can use that signal to start the fan (a bit like the battery
testers that were fitted to the sides of some duracell batteries).

HTH,

Tim.

On 7/11/07, Marcus Warrington <marcus.warrington@xxxxxxx
<mailto:marcus.warrington%40mis-es.com>
> wrote:
> OK.. I need some ideas for a little problem I have.
>
> I am currently refitting our bathroom and I need a way of activating a
> fan but ONLY when some is SAT on the toilet. The fan is a "pan
fan"
that
> extracts air from the toilet bowel to prevent.. err.. smells..
pervading
> the room. I did a mini bulk buy of these a few years ago.. which
reminds
> me, Kevin.. I still have yours in a box somewhere.. let me know your
> address and I'll get them sent to you!
>
> My first thought was a PIR but that would be difficult to restrict 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 to
> pee etc.
>
> Next thought was use an ultrasonic sensor mounted on the wall 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
the
> toilet. Problem is I'm not too sure how "focused" the beam
can be made
> on these devices.
>
> Another thought was to use a stress sensor (or weight sensor ?) on the
> toilet bowel. In some ways this would be the ideal since it would not
> rely on proximity to trigger. Problem is I have no idea what I'm
looking
> for, how much they are, how easy they are to integrate with a relay
etc
>
> Anyone got any ideas ?
>
> Marcus





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