Suggested by an American publication, this circuit has 5 operating conditions indicated in the diagram. The circuit can be designed based on modern equivalent transistors.
This Japanese radio is from the 60s, presenting excellent sensitivity and an output power of 100mW...
Found in Radio Electronics from the 90s, this circuit is based on the 555 directly feeding a small...
Found in 80's Electronic Engineering, this circuit can tune the frequency to be rejected. The power...