While working at NESCO and its successors, Hogan helped develop Fessenden's first crystal detector patent ( 1910 ), a patent on single-control tuning ( 1912 ), and in 1913 discovered the " rectifier heterodyne " which increased radio receiver sensitivity by a factor of one hundred.
42.
He developed an improved detector to pick up this unknown " extra current " based on his new microphone design ( similar to later detectors known as coherers or crystal detectors ) and developed a way to interrupt his induction balance to produce a series of sparks.
43.
Both the Gran Sasso and the Stanford groups have plans to stretch the limits of detection : The Italian team is more than doubling the size of its crystal detector, and next year the Stanford group will bury its detector 2, 600 feet deeper, in a defunct iron-ore mine in Minnesota.
44.
His main complaint was the limited support he got for conducting research, while company officials were upset with de Forest's inability to develop a practical receiver free of patent infringement . ( This problem was finally resolved with the invention of the carborundum crystal detector by another company employee, General H . H . Dunworthy ).
45.
The crystal detector in these early crystal radio sets consisted of an adjustable wire point-contact, often made of gold or platinum because of their incorrodible nature ( the so-called " cat's whisker " ), which could be manually moved over the face of the crystal in search of a portion of that mineral with rectifying qualties.
