This circuit was found in the October 1983 Radio Electronics issue. It is applicable to old analog telephones. The circuit uses common components.
The sensor of this circuit, from an old documentation, is nothing more than an electret...
This interesting circuit for the RDA8851 allows you to obtain two volumes with a simple touch. The...
This circuit was found in a 1977 Radio Shack documentation. Its purpose is to generate 1 Hz...