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.
This circuit shows how to use the TTL IC 7790 to divide a square TTL signal by 7. Duty cycle is...
The AC125 transistor is an ancient germanium type widely used in audio stages as a preamplifier. In the...
Found in a 90s Popular Electronics, it serves both TTL and CMOS logic. The injector can provide 10...