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 is part of an article published in the March 1990 issue of Radio Electronics...
Found in an American publication from 1968, this circuit aims to keep the torque of a DC motor...
In the figure we have the typical circuit of a Baxandall tone control applied to an operational...