This 1967 Philips circuit recognizes a light signal (visible or infrared) modulated by tone. The circuit makes use of components of the time that are equivalent to the current BCs.
The presented logical configuration uses one comparator of the four existing in an LM139 or...
This zero-crossing circuit was found in the 1989 Radio Electronics Experimenter. The Triac must be...
This transformerless low-current power supply circuit was found in the August 1998 issue of...