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 1 kHz triggered oscillator was found in an Electronics Now from the 90s. The circuit fires off...
This circuit, suggested by an Electronics World of 1969, keeps a blinking LED for a while when a...
This relay circuit with a dual channel MOSFET (not very common today) was found in an old American...