Semi-OT: Touch sensors

[Colin McGregor]

--- Tyler Aviss <tjaviss-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org> wrote:
> The touchscreen I already have (the lilliput). What
> I want to do is
> install a frame that will respond to touch by
> turning the display's
> power on or off.

Okay, so as ling as the picture frame is conductive
(either because it is made of a conductive material
(i.e.: metal) or because it got a conductive coating
(i.e.: some types of metal paint)) this is a simple
problem, you want a touch switch tied to the
conductive part of the frame. Here is a website with
10 different touch switch circuits:

  www.discovercircuits.com/C/capacitance-sw.htm

Likely one of the above could do the job for you,
otherwise there are tons of other similar circuits out
there... Do a goggle search on "capacitance switch" or
"touch switch"

Colin McGregor

> On 10/29/07, Colin McGregor <colinmc151-bJEeYj9oJeDQT0dZR+AlfA at public.gmane.org>
> wrote:
> > --- Tyler Aviss <tjaviss-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org> wrote:
> > > Hello All,
> > >
> > > One of my ongoing projects has been to wire up a
> few
> > > mini-ITX boards
> > > as "media control" PC's for around the house.
> > > Basically the idea is
> > > that the board connects to the main household
> server
> > > via PXE-boot,
> > > NFS-mount, etc. It will be attached to a
> lilliput
> > > touchscreen (for
> > > which the linux drivers work nicely, BTW).
> > >
> > > Now the end-plan for this is to move the
> touchscreen
> > > into a picture
> > > frame, with the rest of the wiring in-wall or
> just
> > > otherwise somehow
> > > safely hidden. What I would like to do is have a
> > > touch-sensor attached
> > > to either the picture frame or perhaps a little
> > > plaque attached to a
> > > wooden frame. Like a touch-lamp, the sensor
> would
> > > then turn on the
> > > screen. Depending on how fast I can get my
> boot-time
> > > going with
> > > openbios and "sleep" modes, the motherboard...
> > > although I may just opt
> > > to leave this on 90% of the time since via
> boards
> > > consume very little
> > > power.
> > >
> > > Anyhow, feel free to critique the idea as a
> whole,
> > > but my main
> > > question at this point is:
> > > where do I find the equipment needed to make a
> > > touch-sensitive metal
> > > surface for the frame/plaque.
> > >
> > > Any ideas?
> >
> > I'm not quite sure what your goal is here. Simple
> > on/off control or something a bit more complex.
> >
> > For simple on/off, and a metal plaque your talking
> > the fodder of umpteen hundreds of introductory
> > electronics books / magazines.
> >
> > For a level up from that and any surface, a number
> of
> > years ago I read a construction article in a home
> > automation magazine that had a small LCD module
> that
> > sort of did a touch screen. What they did was
> mount a
> > set of infrared LEDs and light sensors in pairs
> around
> > the LCD module. Fingertip interrupting the beam
> told
> > the automation system that the display was being
> > touched and about over which area of the display
> was
> > being touched. A bit of menu software and presto a
> > home control system by fingertip. One point in the
> > above that I recall them putting emphasis on was
> you
> > want the light sensors at the top and the light
> > sources at the bottom (to reduce false triggers by
> > sunlight etc..
> >
> > For a level above this, I'm not sure ... gut the
> likes
> > of a Palm Pilot?
> >
> > Colin McGregor
> > --
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> 
> -- 
> Tyler Aviss
> Systems Support
> LPIC/LPIC-2
> (647) 477-1784
> --
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