Low battery indicator 555 (CB9551E)

This circuit can operate with different voltages, depending on the zener used. We found it in a 90s American documentation.

Integrator LS141 (CB15192E)
This circuit is from the 1982 SGS linear integrated circuit manual. The LS141 is like to the 741...
FSK Demodulator (CB15902E)
The integrated PLL XFl2211 (Exxar) is used to decode data transmitted by tones R1, C1, C2 and C3...
Double Touch Switch (CB16980E)
This bistable touch sensor circuit uses a relay and is very sensitive. We found it in a 1990...