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 traditional doubler configuration with the 555 can be found in other articles on the author’s site....
This circuit, which appears elsewhere in this section but from other sources, was found in a book...
January 2017 - Mouser Electronics is announcing the availability of the new OptoMOS® CPC1010N...