This circuit operates at a voltage of 1.3 V from a single mercury cell. We found in an old documentation and for the components used the frequency is 500 kHz.
The note sequence for this circuit is achieved through integrated circuits controlled by the 555....
When a voice signal enters this circuit, the volume of the music being played automatically...
We found this configuration in a Radio Shack documentation from 1977. Here we have the way to...