This an old commercial receiver found in a year 1958 magazine. The circuit uses some transformer available that timer and the transistors are germanium types. The circuit is intended to receive MW stations.
Found in an American 1980s documentation, this circuit makes use of a sensor of the era uncommon...
This interesting configuration of optical triggering using an oscillator was found in a 90s...
This headphone amplifier has good gain and high input impedance. The circuit is from Electronics Now and...