We found this circuit in the December 1968 issue of Radio Electronics magazine. The circuit is used with high-impedance magnetic headphones. The transistors are from that time.
The coil is formed by 70 + 5 turns of 6 to 30 AWG wire on a 1 cm to 10 cm ferrite core. The...
This circuit can be used with transmitters in the 3 to 30 MHz frequency range also functioning as a...
This transistorized circuit with germanium transistors was found in a publication from the 1960s....