the hartley oscillator was invented by hartley while he was working for the research laboratory of the western electric company. hartley invented and patented the design in 1915 while overseeing bell system's transatlantic radiotelephone tests; it was awarded patent number 1,356,763 on october 26, 1920. note that the basic schematic shown below labeled "common-drain hartley circuit" is essentially the same as in the patent drawing, except that the tube is replaced by a j-fet, and that the battery for a negative grid bias is not needed.