This circuit is from the 80's documentation. The integrated circuit is from the time but can be implemented with modern equivalents. The power supply must be symmetrical.
This circuit with RTD sensor was found in the Radio Electronics magazine of April 1992. At the...
This circuit was suggested by Motorola in 1980s documentation. The circuit employs an operational of...
This doorbell or buzzer as announced in a 1990s US publication uses an operational amplifier that admits...