Adafruit MPR121 not human contact

[davidgrills]

Hello,

I would like to know if the Adafruit 12x Capacitive Touch shield for Arduino MPR121 can be used to detect object contact and not just human touch.

I would like to detect when my model excavator has a ball in the bucket.
So I imagine putting the MPR121 on the back of the excavator to the Arduino and connecting it there.
Then run a wire along the arm of the excavator to the bucket and connect to taped copper foil there.
If the excavator now charges something, a marble or maybe better a metal ball, can this be detected?
Is it possible to simply change the Arduino code, so that the sensor is triggered by balls touching the foil instead of by human touch?

Another question is, where is the difference between the different capacitive Adafruit boards?
For example there is this https://www.adafruit.com/product/1982 or this https://www.adafruit.com/product/2024

[dastels]

Not likely. Actually, I'll say an emphatic "no". Touch sensors take advantage of the body's (specifically the finger's) dielectric and conductive properties. See https://www.allaboutcircuits.com/techni ... ch-sensing

You should look at other way to sense something in the bucket. Maybe sensing a change in weight (maybe using something like https://www.adafruit.com/product/1361) or using IR beam sensors to detect something in the bucket that breaks the beam. Something like https://www.adafruit.com/product/2167.

Dave

[adafruit_support_bill]

For detecting metallic objects, you might try an inductive proximity sensor.