This noise generator for the audio band was found in a British publication from the 1970s. The circuit can be implemented with modern equivalent transistors.
This circuit, from Texas Instruments documentation, fires a relay when light strikes the...
This circuit was found in documentation from the 1980s. The circuit can be implemented with other...
This circuit is from an 1977 American publication. The coil consists of 30 + 70 turns of 28 AWG...