We found this circuit in the April 1993 Electronics Now magazine. Almost any general-purpose JFET can be used. Power is supplied by a battery (2 x 9V).
This circuit is from an 80's technical newsletter. The circuit can use any general purpose...
This circuit is from old documentation having a gain of approximately 35 dB at 1 kHz with 2.2 mV...
This handy instrument on the maker's bench that does not have a multimeter yet serves to test...