This simple tone control using two transistors was found in an Electronics Today International of the 90s. Transistors are general purpose NPN types, like the BC549 for greater gain.
Found in a European magazine from the 1980s, this circuit can amplify signals from 10 kHz up to...
The circuit in the figure uses the four current amplifiers of the LM3900 to generate a sawtooth signal...
This circuit is from a Radio Electronics magazine from August 1960. It is a commercial circuit for marine...