This filter for the 300 Hz to 3 kHz range was found in an American documentation from the 90's. The operational amplifier is a double 741.
It can be obtained from Mouser Electronics, sensors (receivers) transmitters and benders for...
Suggested by General Electric in a 1965 documentation, this circuit can use the TIC106 as an SCR....
The circuit shown is from the 1994 Linear Applications Handbook from National Semiconductor. The...