This amplifier uses a 1975 integrated circuit, which is uncommon today. The circuit has a gain of 30 dB and uses a transformer-less output with 9 V power.
We found this protection circuit for the power supply in a 1992 documentation. This circuit has...
I found this circuit in a documentation for radio amateurs from 1975. The FET could be the BF245....
Found in an American 80's documentation, this circuit can use common FETs like the BF245 and cover...