I made a self osc class D amp according to UCD topology. It works well with no distortion.I use 2N5401/5551 as small signal transister an IRF520 as power mosfet.
But there is a problem.It seems it is very sensitive to input.when I put my finger near the input pin then there is a noise in the speaker.
And if I connect computer or phone as an audio source with it then the speaker becomes noisy.even if I turned off the audio player in the computer. The noise is hearable within half a meter.
The noise sounds not like white or pink audio band noise. It sounds something like the mirror-image-frequency interference jam in the Super heterodyne radio receiver.because the noise often change frequency and sounds like howlround.
Does anyone encountered this problem?
But there is a problem.It seems it is very sensitive to input.when I put my finger near the input pin then there is a noise in the speaker.
And if I connect computer or phone as an audio source with it then the speaker becomes noisy.even if I turned off the audio player in the computer. The noise is hearable within half a meter.
The noise sounds not like white or pink audio band noise. It sounds something like the mirror-image-frequency interference jam in the Super heterodyne radio receiver.because the noise often change frequency and sounds like howlround.
Does anyone encountered this problem?
You need terminate the inputs. A resistor between 10-47k on the input in parallel with a 1nf or so capacitor should make it silent with no source.
after adding a R-C-R 1k-5nf-1k pi network to the input I sucssesefully down the noise. now it is only hearable when I put my ear near the speaker. thanks all of you!
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