This 3-transistor buzzer or buzzer is a classic type found in the July 1998 issue of Electronics Now magazine. The power rating depends on the output transistor.
This circuit was found in a Popular Electronics from the 90's. The output signal can be applied to a...
A small loudspeaker (2.5 or 5 cm) can be used as a low impedance microphone. A preamplifier and...
This flip-flop circuit with general purpose transistors was found in American documentation from...