Found in a 1992 book, this circuit is intended for operation with audio signals. Equivalent operational amplifiers can be used. The optical coupler is an unusual type today.
Found in documentation from the 1980s, this amplifier uses an integrated circuit from the time....
This is a one-channel application for the Texas Instruments TMP390 sensor obtained directly from...
This moisture-activated relay was obtained from an American documentation from the 1980s,...