The circuit shown is from the National Semiconductor Linear Applications Handbook of 1994. using ADC0808. The circuit can handle data from up to 4 transducers with an 8-bit output.
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...