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 circuit was found in an old 1980s valve documentation. The circuit can directly replace a...
I found this circuit in an ond publication from 1958. The transistors are germanium types but the...
This circuit show the performance of a GraetzBridge or Diode Bridge usedin full-wave rectifers....