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.
This circuit is intended to trigger an alarm when the input voltage exceeds one value and to...
This circuit, found in a 1986 documentation, uses an optical sensor to count pulses and, in its...
This circuit was found in Delco documentation from 1966. The components are from that time....