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.
This circuit was found in Intersil's 1992 documentation consisting of a test for ADc0801 and...
This 60's shield or driver employs germanium transistors. The circuit is from a 1960 Gernsback...
The circuit shown in the figure on the right can be used on a data transfer bus with the use of an...