This circuit was found in an American documentation from 1969. The circuit is a multi-indicator with resistors typically 47 k for R1 and 100 k for the others.
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...