The configuration shown allows to obtain a high voltage gain for FETs. FETs can be BF245 or MPF102. The circuit is from the 1977 National Semiconductor FET Databook.
The cut-off frequency of the filter shown in the figure can be adjusted to values between...
This circuit was found in a Popular Electronics from the 90s. The components used are all common...
This circuit uses a dual floodgate MOSFET not very easy to obtain today. Its handling is very...