touch plate switches???

[Bob Richards]

I'm going to build a line preamp and would love to use touch plate switching technology. I researched chips that would support this, but they all seem to require a CPU. I'm trying to find touch plate chips that put out a separate control voltage for each touchplate, something I can buffer and drive a small latching relay with. or at least a binary output that I can decode with a binary to base 10 converter chip. Any help on this would be appreciated much.

 

[CopperTop]

Hi Humdinger

If you search for capacitive touch sensor ICs you should find plenty. Have a look at this one for example:

ATMEL|AT42QT1010-TSHR|SENSOR, TOUCH, CAP, 1CH, 6SOT | Farnell United Kingdom

 

[macboy]

The Azoteq IQS127D implements a single touch- and proximity-sensitive button (even through a substrate like glass or plastic) and has simple to use "active on" outputs. One problem is that it comes only in a tniy little SOT-6 package, and another problem is that it's hard to find. One of my favorite component/gadget stores carries it in a pack of 5 including DIP adapters.

 

[Bob Richards]

Thanks much. I've also found a few others on the web that appear to be useful for someone who doesn't write code. I've wanted to use touchplates for decades, I think since I saw the movie A Clockwork Orange in the late 60's. Now I just need a good clear conductant that you can paint onto frosted plexiglas. That way I can backlight the touch plate/knobule fully, with an LED. Anyone know where I can get paintable (dipable) clear conductant? This is going to be SO COOL!!!

 

[CopperTop]

I don't know about clear conductive paint, but you can buy sheets of clear acetate coated in Indium Tin Oxide - I think I even got some free samples from somewhere. You could cut pieces out and place them behind your perspex panel. Alternatively you can make electrodes from extremely fine wires which would be practically invisible.

 

[Steerpike]

If you want a 'touchable' transparent front plate, you might try infa-red LED/phototransistor reflective detectors. Then you just have a piece of tinted plastic or glass with no conductors required.
E.g. http://docs-europe.electrocomponents.com/webdocs/02af/0900766b802aff23.pdf

 

[Itsmee]

This might be what your looking for

Electronics Projects Vol. 22 (With CD) - Google Books

or you could use a PIR detector