While looking for a perimeter alarm I found this -

Seal devices against all possible contamination
Detect switch 'pressing' through 50mm of panel (32 switches per sensor chip)
Measure all sorts of fluid levels
Detect approach to and crossing of boundaries
Directly operate via logic output, or
Communicate via uart or SPI @ 5MHz
etc, etc, etc starting at US$6.00 in single quantities (110 series)

http://www.qprox.com/background/applications.shtml

Be sure to download the White Paper and the Product Summary Guide


WOW !

Bye.

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