This basic CMOS 4001 circuit was found in the April 1976 issue of Radio Electronics magazine. The circuit generates rectangular signals, and the components can be changed to obtain other frequencies.
This 2000 circuit can work with one of the many infrared remote-control transmitters described in this...
This receiver for listening on the phone was found in a Japanese magazine in 1967. The circuit uses...
The circuit shown in the figure is suggested by Intersil (www.intersil.com) and makes use of the...