This circuit uses a 555 (according to the diagram) to generate 50 ms tone bursts at a frequency of 1.5 kHz. The circuit is from an 80's Electronic Design.
This circuit can be used as a shield for microcontrollers. The circuit is from American...
This car battery power supply was found in the June 1990 issue of Radio Electronics magazine....
August 2017 - STMicroelectronics' BlueCoin development environment is available at Mouser...