This circuit was found in a 80s American documentation. The zener diodes determine the points of action of each stage and the transistors can be general purpose types.
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...