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Thread: Grounding issue?

  1. #1

    Grounding issue?

    Hi all,

    I think I have a ground problem. I have a Teensy 3.2 and audio adapter set-up as seen in the image. The touch pads work when plugged into USB power or if i touch a ground connection or some parts of the circuit (the 1/4 jack socket, the side of the screen etc).

    I did read in another post Paul asked what happened when you touch a wire (gently) from the ground on the teensy to the ground on the audio output (in this case the mono audio amp out to the speaker) and this make the circuit crackle and die.

    Is there any way to make this work without adding a ground wire that you have to touch as well as the pad or doing capacitive sensing with 2 pins instead of the touch pins?

    What am I missing?



    Click image for larger version. 

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  2. #2
    Senior Member+ Theremingenieur's Avatar
    Join Date
    Feb 2014
    Colmar, France
    One path could be operating the circuit not from batteries but from a wall plug adapter which provides loose but enough capacitive grounding for stable operation.
    The RF based capacitive touch engine of the Teensy works similar as a 1940s heterodyning radio which also needed an extra ground connection for good reception.
    If you can‘t provide extra ground and you must stay with batteries, the state of the art solution would be to work with split electrodes in a form that you easily touch always both halves. The second half of all touch electrodes could be connected together and linked to the Teensy GND via a 4.7nF capacitor.

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