We found this circuit in a documentation for radio amateurs from the 70s. The transistors can be the BC548. With it, small speakers of 4 or 8 ohms can be used as microphones.
The transistors of this old circuit from the 60s can be the BC548, in a current version. The...
This electronic soldering gun circuit was found in the December 1998 Electronics Now magazine. The article...
This circuit was found in an American documentation from the 90's. What it does is provide at the...