This circuit uses a 100 kHz crystal, but nearby frequencies can be obtained with appropriate crystals. Components are still common today.
This circuit was found in a 1990 documentation. It uses very common transistors still today and...
This circuit makes the RIAA equalization for signals obtained from a turntable for signal recovery in other...
This circuit, found in a publication from the 1980s, can have its output voltage determined by the...