The transistors of this circuit found in an English 1980s documentation may be the modern BC548 equivalents. The circuit is battery powered and the earphone must be crystal.
This simple oscillator with just one transistor has a frequency determined by the characteristics of the...
We found this circuit in the January 1979 issue of Radio Electronics magazine. Components are...
Found in a 90’s Radio Electronics magazine, this circuit uses a component from the time, difficult...