This circuit triggers in 100 microseconds in case of excess voltage. The adjustment is made in the pot. The circuit was found in 1969 documentation.
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...