Found in Popular Electronics from the 90's, this circuit uses 555 integrated and common transistors to generate two tones determined by push buttons S1 and S2.
Found in documentation from ON Semiconductor, this circuit provides a rectangular output signal with...
We found this circuit in 1964 General Electric documentation. The circuit works with mechanical...
This very low frequency circuit was found in a 1964 Electronic Design. Transistors may be modern...