Platform for creating and sharing projects - OSHWLab

i also follow robert firanec

First I would implement high pass filter to the audio input, if there is something like motor interference coupling to the audio signal. 1Hz signal is easy to remove with a high pass filter. High frequency hum might become from the ICL7660. You create a negative rail by switching C9 cap. I had the same effect when I used that chip. You can check it out from my published project. It was audio mixer project. Also, you might get mains frequency hum which is pain in the back side to filter out. But because main frequencies are around 50Hz-200Hz with its harmonics, then making a high pass filter on the input might help with that too. The rest of the possible interference might become from the layout. I highly suggest using start point grounding in audio circuits. I would be very interested to take a look at the layout? I may find something there.... Regards, Markus Virtanen HW / Electronics Designer

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There is a few 3D models in the user contributed library, but not really a good quality. So, basically Adafruits module is available there.[Picture]