This circuit was found in a Popular Electronics from the 90s. The transistors are general purpose, and the gain depends on the ratio between R2 and R1.
In the figure we have a typical polarization circuit for MOSFETs with a high impedance...
Equivalent transistors, like the BC548 and BC558 pair can be used in this circuit that we find in an...
The circuit presented is from an old magazine having been translated and published in a national...