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 circuit uses integrated 555 and an amplification step with transistors, as we can see in the...
This circuit uses components that are still common despite being from 1995 documentation. The circuit can...
This circuit was obtained from American documentation from the 1990s. The transformer can be a car...