This circuit is from a Radio Electronics from the 90's. The integrated circuit is from the time and the boost gain is 20 dB.
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...