This simple circuit needs a high gain stage to compensate for losses. It consists of a passive tone control obtained from Electronics Today International of the 90s.
We found this project in a 2002 documentation. The transistor amplifier has a power of a few watts...
This circuit simulates the call tone of a telephone. The transducer is a high impedance capsule, and...
This circuit triggers three incandescent light bulbs following the audio signal applied to its...