This circuit from Motorola is from 1968, appearing elsewhere on this site. The transistors admit equivalent and the relay is of the sensitive type for low voltage, according to the power supply.
This radio's transistor is powered with the signal's own energy, producing its amplification....
Found in a 90s Electronic Design, this circuit can be used as a shield in current projects. The...
The integrated circuit used in this regulator is not very common today. The circuit is from old...