The sensor of this circuit is a photodiode. Equivalent operations can be used, and the instrument can be replaced by the lower current range of a standard multimeter.
This interesting idea was obtained in a 1982 documentation and can be used for special effects in...
This is another of the many circuits we have with the 8038. The circuit is from the Radio...
This LC oscillator was found in English documentation from the 1990s. JFETs may be general-purpose...