tantudaisu
Member level 3
I have a small electronic device with speaker. Device is powered by standard, general purpose impulsive AC/AD power adapter (12V, 1A). When I first powered it up, I heard a switching noise from speaker. Then I tried my Lab power supply, there were no angry switching noise. So I decided to investigate how can switching noise could be reduced. I connected oscilloscope's ground to my devices PCB board and noise disappeared, I even cant measure noise frequency, when disconnected GND noise appeared again. Can anybody explain whats the effect, and how can I solve noise problem? Does it contain with common mode or diff mode noise?
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