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.
In a voltage follower, the gain is unitary, and the input impedance is very high. The output...
This circuit, from an old 1988 publication, generates bars on the screen of an old analog TV for...
This circuit is from a Motorola integrated circuit manual. The integrated used is no longer common...