This harmonic oscillator controlled by crystal was found in an American documentation of the 90's. The circuit uses transistors of the time. Current equivalents can be used.
This filter for scratched disc noise was found in an English documentation from 1989. The...
Mouser Electronics owns the Littelfuse SP3422 low-capacitance TVS diode arrays. These components are...
This two-tone decoder has a bandwidth of 24%. The circuit is from a 1994 Electronics Now. The...