This astable multivibrator was obtained from a Mullard documentation from 1960. The components depend on the used transistor and on the frequency, as shown in the table next to the diagram.
This balance control for the channels of a stereo system was found in a 1969 Mullard...
The article that teaches the assembly is from a Radio Electronics issue from July 1969. The...
Found in old English documentation, this circuit is still current. The circuit trips with a sound...