Vinod writes, “This is an FM transmitter directly made from STM32F407 discovery. It transmits the wav file stored in internal flash via FM at 100MHz.
The modulation over here is happening by a tricky feedback from the analog output of the same mcu to the crystal oscillator there by disturbing the crystal frequency and creating frequency modulation.
It works nicely than expected an getting a very good range and comparable to normal single transistor FM transmitter.
More details at Vinod blog.
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Check out the video after the break.
What an awesome hack!