We found this circuit in a 1967’s Electronics World. The circuit can be made with modern equivalent transistors. The selection is made by the tuned coil.
This simple tester was found in a Popular Electronics from the 90s. The circuit is powered by two...
In addition to tone control, this circuit of the SGS 1982 linear integrated circuit manual has a...
This common crystal oscillator configuration was found in a 1980s American documentation. The...