Found in a 1964 Electronic Design, this circuit protects the transistors of a complementary output stage. The diodes limit the current in the complementary pair.
This small transmitter with 2 transistors can reach several hundred meters using a 30 to 70 cm...
The integrated circuit used by SGS is not common today. The circuit is from the 1982 SGS linear...
We found this circuit in an American 1980s documentation. The transistors can be equivalent as BC548...