This filter is from a 1977 publication. The circuit employs three 741 or other operational amplifiers. The supply must be symmetrical and the components with (*) are low tolerance.
This ultra-simple circuit has the frequency determined by the LC network. Any general purpose JFET...
Found in American documentation from the 1990s, this circuit uses coils with multiple outlets to...
I found this circuit in a 1986 English magazine. It can still be easily assembled, exchanging Q1...