We found this circuit in the Radio Electronics magazine of February 1993. The main integrated circuit is from that time and the power supply is made with voltages of 6 to 15 V.
We found this amplifier circuit for inductive audio pickups in a documentation from the 70s. The...
This oscillator generates a signal of approximately 400 Hz, which has its symmetry adjusted...
This circuit indicates the volume of an audio signal in a different way. The circuit is from 1997...