Found in an English publication in 1969, this circuit has a 600 kHz pass band. Ferranti's transistors support modern equivalents.
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...