Wien studied under Helmholtz and Kundt.[1] He invented the "Löschfunkensender" (generator of slightly weakened electromagnetic oscillations) during the years 1906 to 1909 and the Wien bridge in 1891. Many articles incorrectly attribute to Wien the invention of an oscillator bearing his name, but at the time of the invention of his bridge circuit, electronic amplifiers (a prerequisite to making electronic oscillators) did not exist. William Hewlett, co-founder of Hewlett-Packard, was the first to use a Wien bridge as a feedback network around a vacuum tube amplifier to create an oscillator in 1939.