Any small sound amplifier from 200mW to 1W can be used in this simple circuit. Or circuit of two 80s based on a trigger like 555.
In the figure below we have the typical circuit of an automotive star alternator with the...
This simple pass-through circuit was obtained in an old documentation, but it is still up to date...
This circuit was obtained in a 1974 National Semiconductor components and circuits manual. The...