Hi,
The spike is about 4ms after the rising edge of the pink signal?
Is this true?
And is it always that "4ms"
Then I assume the pink signal controls something like a relay or so...?
****
But the reason and the filter depends on a lot of things.
I asume it is an EMI pulse.
Then the pulse may be induced by wire or by air.... We can´t see/know this, because we dot see your application.
There´s a chance that the signal is (just) coupled by the scope´s wires.
Klaus
Hi,
show us a photo of your application. On this photo we want to see:
* all your GND wiring
* all your scope connections
* the "switch" (we still don´t know what this is)
Give explanations to this photo.
Klaus
We even don´t know where you want to install these parts.Would an RC 330 ohms and 1uF ceramic help?
Would an RC 330 ohms and 1uF ceramic help?
Depends how it is connected. RC filter is lossy.Would an RC 330 ohms and 1uF ceramic help?
Unfortunately the photos don't show the mounting position and wiring of the Arduino board. If the Arduino has no other connections than USB and the two output wires, it's most likely that the interferences are entering the system through external USB cabling. I guess you can't perform any tests without connecting a computer. You might try common mode choke cores for the USB.
Another possible entry path is the external signal wiring, not clear if it was already connected during the tests.
Like dick_freebird I'm awaiting clarification about "DAQ board upset".
Hi,
In this picture there is a GND_loop.
Via USB_GND, Power-, GND.
Try to wire it as a star connection instead.
Klaus
Hi,
There is the red loop.
And most probably there is a second one across the power supplies and the earth GND.
This usually is capacitvely coupled...no loop for DC.
View attachment 150135
Klaus
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