The magnifying transmitter is an advanced version of the classic Tesla coil. It is a high power harmonic oscillator that Nikola Tesla proposed for the wireless transmission of electrical energy. In his autobiography, Tesla stated that "...I feel certain that of all my inventions, the Magnifying Transmitter will prove most important and valuable to future generations." The magnifying transmitter is an air-core, multiple-resonant transformer that can generate very high voltages. Tesla originally termed it self-regenerative resonant transformer, a term that is no longer in general use.