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 Radio Electronics from the 90s, this circuit has frequency and active cycle adjustment....
This circuit is the receiver for the previous remote-control transmitter. We found it in the same...
Found in 90s Popular Electronics, this circuit uses common general-purpose transistors in a...