Thanks God who gave us the mighty Scope.
You have a **gross** case of oscillation, which being around 50kHz isn't audible ... by itself that is, but it overstretches the gain stage big time and SWAMPS the audible signal.
You can not hear 50kHz but yes what it does to signal.
In fact most certainly oscillation gets triggered ON-OFF by audio signal and we hear that continued stsrt-stop as "splat".
Nice little scope, it tries to help and tells what "it" finds.
I would call that waveform, specially the 8th one: 440 Hz (what you are injecting) mixed with 50 something kHz (oscillation); but I guess TEK just counts zero crossings so it reports the grand total, 50kHz + 440Hz which is basically 50kHz.
Thatīs why even with sophisticated instruments we still NEED the Human brain to separate chaff from wheat.
Ok, we need to kill that oscillation and we cure 90% of our problems, if not 100%.
Too busy now but will open the schematic later and suggest some action.
You have a **gross** case of oscillation, which being around 50kHz isn't audible ... by itself that is, but it overstretches the gain stage big time and SWAMPS the audible signal.
You can not hear 50kHz but yes what it does to signal.
In fact most certainly oscillation gets triggered ON-OFF by audio signal and we hear that continued stsrt-stop as "splat".
Nice little scope, it tries to help and tells what "it" finds.
I would call that waveform, specially the 8th one: 440 Hz (what you are injecting) mixed with 50 something kHz (oscillation); but I guess TEK just counts zero crossings so it reports the grand total, 50kHz + 440Hz which is basically 50kHz.
Thatīs why even with sophisticated instruments we still NEED the Human brain to separate chaff from wheat.
Ok, we need to kill that oscillation and we cure 90% of our problems, if not 100%.
Too busy now but will open the schematic later and suggest some action.
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