This circuit for dual-gate MOSFET was found in a 90’s Popular Electronics. The coils are according to the frequency range that must be amplified.
This circuit, from the 90's, is intended for operation with vinyl record players of the time, as...
Using a zener diode it is possible to change the linearity of the scale of an analog instrument by...
Found in American documentation from the 1980s, this circuit prolongs the ringing of a doorbell or chime...