Suggested by Siliconix in documentation from the 90s, this circuit can present gains of digitally selected by the input going from 1 to 1000. The circuit can be adapted to work as a shield.
The AC125 transistor is an ancient germanium type widely used in audio stages as a preamplifier. In the...
I found this simple circuit an English magazine from 1984. The circuit can be easily assembled by simply...
The LMV321 is a low voltage operational amplifier from ON Semiconductor. The following diagram,...