Based on the Linear Technology LTC2054, this -48 V circuit was found in a 2005 manual. The circuit is powered with 5 V and can be used as a shield.
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...