Used with infrared remotes at the time, this circuit was found in a 1991 RE Experimenter Handbook. It may not work with the faster remotes control used today.
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...