We found this circuit in a Radio Electronics from December 1963. The circuit combines valves and transistors and has a high input resistance. The circuit is powered by two batteries.
This is the circuit published in the August 1973 issue of Radio Electronics magazine announcing its...
This circuit can be used to add a delay to a logic signal as shown by the input and output...
This tone control was obtained in the Audio Handbook of the National Semiconductor of 1977. The...