Using a 4046 PLL this circuit recognizes a 1.6 to 1.8 kHz tone by driving an output LED. The circuit is from a Radio Electronics from December 1989.
This circuit causes an incandescent lamp to flash according to the input audio signal. The SCR...
This circuit is from a factory documentation (National Semiconductor) of the 80's. The power...
The A3906 integrated circuit from Allegro MicroSystems (www.allegro.com) consists of a single...