Black Knight
Williams, 1980You're currently viewing posts by Pinsider G-P-E.
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^^ what wayout said. You were getting the noise from rectified AC induced into an audio trace.
Plus if the board designer ran one or more of his audio traces too close to noisy power traces without guard tracks - you will get noise induced from trace to trace. I suspect this is why removing the FWB rectifier out of the active circuit and using a separate DC source cleaned things up.
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Omaha, NE