RE: xPL-LCD PICS

["Ward, David" <DAvid.Ward@xxxxxxxxxx>]

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@xxxxxxx]
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@xxxxxxx>
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@xxxxxxx]
> 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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