This commercial radio with 3 earphone listening transistors was manufactured in Japan in the 1960s. The medium-wave circuit uses germanium transistors and is powered by a 9 V battery.
This circuit was found in a 1992 documentation and has excellent sensitivity, using components that...
We found this circuit in an old American documentation. The circuit applies to modern equivalent...
This circuit was found in an English publication from the 80's. It triggers a buzzer (with...