Found in 90s Radio Electronics, this shield can control high voltage loads in the power grid. Isolation is guaranteed by the use of an optical coupler.
Suggested by a 1966 publication, this circuit applies a 60 Hz signal to a transistor to test its...
This circuit is indicated to operation with piezoeletric transdicers or other with high impedance...
Two operational amplifiers are used in this source obtained in an American documentation...