This filter has the components calculated for the frequency of 1 kHz but can be changed. The input resistor can be 100k and the source symmetrical. Any operational amplifier can be used.
The integrated circuit used in this project is not common today, but it can be implemented with more...
Found in an American publication from 1969, this circuit can be adapted to be used as a shield....
This current meter with many scales was found in a 80s American documentation. The operational amplifier...