With this system you can disconnect phone lines in case of need for protection. The circuit is from a 1989 documentation working only with analog lines.
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....