This simple audio and RF signal tracker was found in a Japanese publication in 1967. The transistors are made of germanium and the headphone is made of crystal.
This normally open, two-terminal, high-sensitivity circuit was found in General Electric's...
Bubba's oscillator, shown in the figure, is another type of phase shift oscillator, but it takes...
This sensitive electroscope uses a MOSFET 3N128 and can detect electrostatic charges of objects....