This circuit was obtained from an American documentation from the 80s. Integrated circuits are from that time and are not easy to find today.
February 25, 2015 - Mouser Electronics, Inc. today announced their new Robotics Technology site....
This circuit was found in an Australian publication from 1991. The circuit emits a tone as well as...
This circuit is from an old publication but can be implemented with modern silicon transistors such as...