This circuit filters low frequency noise from the turntable motor. We found it in a 1989 documentation. The font doesn't have to be symmetrical, but it should have excellent filtering.
This circuit was found in an American 1980s documentation. The integrated circuit used is uncommon...
We found this circuit in a Radio Electronics magazine from June 1992. The circuit has a power...
This simple audio and RF signal tracker was found in a Japanese publication in 1967. The...