With this circuit found in an American documentation from 1969 it is possible to vary the selectivity (Q factor) of a tuned circuit. The operational is from that time.
Suggested by General Electric in a 1980s publication, this circuit is intended for coupling...
We find this circuit in the 80s used integrated circuit manual itself. The integrated circuit is not...
This simple musical instrument was obtained from a 1967 magazine. If the original transistors are...