This third-order Butterworth filter was found in American documentation from the 1980s. Formulas for component calculations are attached to the diagram.
This circuit is from the 1982 SGS linear integrated circuit manual. The LS141 is like to the 741...
The integrated PLL XFl2211 (Exxar) is used to decode data transmitted by tones R1, C1, C2 and C3...
This bistable touch sensor circuit uses a relay and is very sensitive. We found it in a 1990...