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 circuit uses an unusual electromechanical component: a mechanical blade resonator. The...
This circuit from a Japanese publication in 1968 uses germanium transistors from the time like the...
Found in a 90s Electronic Design, this circuit can provide a relatively high-power output. The basic...