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Topic: Capacitive sensor: sensitivity problem (Read 5 times) previous topic - next topic

Grumpy_Mike

There are a number of techniques you can use.
Start off by looking at this:-
http://en.wikipedia.org/wiki/Capacitive_sensing
or perhaps better:-
http://www.eetimes.com/design/industrial-control/4371081/An-introduction-to-Capacitive-Sensing-Part-I

Then there is this from Microchip
ww1.microchip.com/downloads/en/AppNotes/01101a.pdf

Cypress include cap sensors on some of their processors
www.cypress.com/?docID=3346

and there is
www.fujitsu.com/.../fujitsu-whitepaper-capacitive-touch-sensors.pdf

So you see many people are working on this and the best technique depends on what exactly you want to achieve.

ciavaldp

Thank you, Grumpy_Mike this helps a lot :)

dc42

For measuring low capacitances, I use the capacitor in a 555 oscillator circuit, then measure the output frequency using the Arduino. Use the CMOS version of the 555, it allows you to use higher value resistors.
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