Re: xPL-LCD PICS

["Gary" <questuk1@xxxxxxxxxxx>]

Hi David,

I have read the datasheet on qprox sensors and cannot find the exact
info i require!

They mention Cx, that is attached to the external sensor plate. Now,
is this the natural capacitance of the sensor, or a capacitor you add
to the sensor then attach to ground?

Also there is a difference in sensor range if I attach the -ve
terminal of a battery operated circuit to ground ....(your finger can
be 3mm away from sensor and it still works).

But if i do not connect the -ve terminal to ground the distance is
about 1mm, any ideas how to improve the sense distance as i would like
it to be just a battery operated device, with no ground connection.


Thanks

Gary




--- In ukha_d@xxxxxxx, "Ward, David" <DAvid.Ward@s...>
wrote:
> I made a little PCB for a previous employer that had a QT11x socket
(I used 115s because they had the no-recalibrate option) and a relay
> On that board I had two 78L05 regulators to try and prevent any
relay switching noise interference with the QT, it may have been
overkill but I only had one chance at the PCBs and it needed to work
>
>
> http://www.apple.com/airportexpress/
>
> fantastic little wireless access port/bridge/print server/analogue
and digital audio streaming thing
> and if you use a keyspan USB IR receiver it will send the IR to the
host PC via the Airport express
>
> trouble is that Apple have really designed it to be used with a WiFi
laptop as a 'remote control'  and it only streams audio in Apple loss
less format
>
> DVD Jon created Justeport to stream any AAC loss less file to it and
Rogue Amoeba have airfoil, which routes any Mac audio via the airport
express
>
> I think xPL a xPL <-> iTunes connector might be the answer, 
then a
xPL enabled LCD like yours or IR and pronto would give me the remote
control I need
>
> Dave
>
>
>
>
> -----Original Message-----
> From: Frank Mc Alinden [mailto:fmcalind@b...]
> Sent: 24 March 2005 10:42
> To: ukha_d@xxxxxxx
> Subject: Re: [ukha_d] xPL-LCD PICS
>
>
>
> Hi Dave
>
> > I have to admit that the QT110 and QT115 that I used to use to
control
> > interactive exhibits 'hardly' ever false triggered once set up.
>
> This could be my problem....not setup properly.....
>
> > I also used to run the QT devices from a separate linear
regulator IC
> > and associated filter caps, a 1R resistor in series with the
supply to
> > the regulator could also help blocking noise by creating a
slightly
> > higher impedance path on the supply.
>
> It was being powered by the pic icd so im assuming that would be
pretty
> clean....
>
> > IIRC the cap should be matched to the capacitance of the
> sensor,  I used
> > to have a QT11x demo board (the one with the two AAA batteries) 
and a
> > range of caps that I used to determine the capacitance required
for a
> > particular sensor,  and a piece of SIL strip socket on the
> final circuit
> > to plug the caps into.
>
> So how was it determined...??? I suppose i should have a real
> good read of
> this qprox stuff....
>
> > Could it be possible that the banana plug sensors are the 'wrong
way
> > around' for the QT to operate reliably?  I.e. the large area
> which would
> > be more sensitive to touch is inside your box
> > It may be better to have a sensor that is wider than it is deep,
for
> > example's sake just use a washer with a wire connecting to
> the QT device
>
> Quite possible...but  im also using the banana plug as an led
> holder ....
>
> > HTH and keep up the inspirational work ;)
>
> Thanks for the feedback and pointers
>
>
>  >BTW I like the LCD where did it come from?   I was luck enough to
be
> > given an Airport Express for Christmas and I am trying to think
of the
> > neatest solution to control the iTunes server remotely
>
> Got it here in Melbourne...PLED LCD  .......no backlit required.....
>
> Whats a Airport Express...???
>
> Frank
>
>
> ----- Original Message -----
> From: "Ward, David" <DAvid.Ward@s...>
> To: <ukha_d@xxxxxxx>
> Sent: Thursday, March 24, 2005 9:25 PM
> Subject: RE: [ukha_d] xPL-LCD PICS
>
>
> >
> > Frank,
> >
> > Good idea, a software filter could help, ignoring nonsensical
presses
> > whilst in menus etc would also make it more robust.
> > I have to admit that the QT110 and QT115 that I used to use to
control
> > interactive exhibits 'hardly' ever false triggered once set up.
> >
> > IIRC the cap should be matched to the capacitance of the
> sensor,  I used
> > to have a QT11x demo board (the one with the two AAA batteries) 
and a
> > range of caps that I used to determine the capacitance required
for a
> > particular sensor,  and a piece of SIL strip socket on the
> final circuit
> > to plug the caps into.
> >
> > I also used to run the QT devices from a separate linear
regulator IC
> > and associated filter caps, a 1R resistor in series with the
supply to
> > the regulator could also help blocking noise by creating a
slightly
> > higher impedance path on the supply.
> >
> > What QT device(s) are you using?
> >
> > Just had another though
> > The QT devices operate by 'transferring charge' from the
> sense capacitor
> > to the in circuit capacitor - when the voltage on that cap
reaches a
> > threshold the output operates. The sense cap is formed between
your
> > finger and the sense plate.
> >
> > Could it be possible that the banana plug sensors are the 'wrong
way
> > around' for the QT to operate reliably?  I.e. the large area
> which would
> > be more sensitive to touch is inside your box
> > It may be better to have a sensor that is wider than it is deep,
for
> > example's sake just use a washer with a wire connecting to
> the QT device
> >
> > If I get a chance (and I can find them) I may have a play with
the QT
> > device I have around here somewhere
> >
> > HTH and keep up the inspirational work ;)
> >
> > Dave
> >
> > BTW I like the LCD where did it come from?   I was luck enough to
be
> > given an Airport Express for Christmas and I am trying to think
of the
> > neatest solution to control the iTunes server remotely
> >
> >
> >
> > -----Original Message-----
> > From: Frank Mc Alinden [mailto:fmcalind@b...]
> > Sent: 24 March 2005 09:57
> > To: ukha_d@xxxxxxx
> > Subject: Re: [ukha_d] xPL-LCD PICS
> >
> >
> > Hi David
> >
> > > Have you considered putting a washer around the socket?
> > > It could go in front or behind the panel....
> >
> > Yep tried that yesterday , behind the panel didnt make any
> > difference....I
> > also changed the capacitor from 4n7 to 10nf...but it  started
false
> > triggering...?? generating heaps of xpl trig messages.....Are you
> > suppose to
> > debounce the qprox outputs ?? ..... i now have a 50msec debounce
....
> >
> > Frank
> >
> > ----- Original Message -----
> > From: "Ward, David" <DAvid.Ward@s...>
> > To: <ukha_d@xxxxxxx>
> > Sent: Thursday, March 24, 2005 8:48 PM
> > Subject: RE: [ukha_d] xPL-LCD PICS
> >
> >
> > >
> > > Very nice Frank
> > >
> > > Have you considered putting a washer around the socket?
> > > It could go in front or behind the panel....
> > >
> > > Dave
> > >
> > > -----Original Message-----
> > > From: Frank Mc Alinden [mailto:fmcalind@b...]
> > > Sent: 24 March 2005 09:13
> > > To: ukha_d@xxxxxxx
> > > Subject: [ukha_d] xPL-LCD PICS
> > >
> > >
> > > Hi All
> > >         I have now put some pics on my website of the
> xPL-LCD  ....If
> > > interested in having  a look..Follow the xPL ..link........
> > > http://skybax.rapidhoster.co.uk/~armagh/index.html
> > >
> > >
> > >
> > > Frank
> > > www.armaghelectrical.com.au
> > >
> > >
> > >
> > >
> > >
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