This circuit with output powers of 2 to 3 W depending on the power supply was found in the magazine Radio Electronics of April 1990. The speakers are 8-ohm.
This 2004 circuit is based on the ionization effect that occurs in old incandescent lamps with...
This circuit memorizes through an LED indicator if your phone was used during your absence. The...
Found in a 1969 Electronics World, this circuit generates low frequency signals with two...