my copper foil capacitive sensor works fine (wonderfully) with USB to a computer but does not detect at all once i use a 9v battery. It then goes all haywire and keeps buzzing (continuous detection) when i touch on some of the resistors with my fingers. Can someone explain this? Thanks
9V batteries are for smoke alarms, and are generally unsuitable for Arduinos.
Fresh ones will usually work for a few minutes, though.
Yes it is due to a lack of a good ground. A capacitive sensor works by measuring the capacitance between the sensor and ground. With a computer attached you have a large ground already, with a battery you don't.
So add some foil close to your sensors and connect it to the ground of your Arduino.
I move this post away from where you put it to here. Basically you put it in the wrong place.
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thanks let me test that out
the foil doesnt seem to work as well. any other suggestions on how i should better ground? I realised it works best when i touch the bottom of my 9v battery to ground it. but any way i can ground it without touching the battery
Can you say or show what you have tried?
Can you say what sensor chip you have used?
There are several techniques for touch sensing, what one are you using?
Have you seen this simple example?
Simple Touch Sensing
Or this more complex one?
capacitive sensing survey
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