We found this circuit in an old American publication from the 1980s. Transistors can be general-purpose types like the BC548, and the tuning frequency is given by the L and C components.
This alarm oscillator was found in the December 1974 issue of Radio Electronics magazine. The...
We found this small audio amplifier in the November 1999 issue of Electronics Now magazine. The...
This circuit is a continuation of the previous one, serving as a protector against overloads in...