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 source allows the supply of laser diodes with voltages above 11 V. The circuit is from French...
This circuit uses an 18 MHz crystal to generate 36 MHz signals. We found it in an 80's...
This circuit monitors the current in the negative line. The circuit is from a 2005 Linear...