Electronic circuits > Radio > Coilless FM transmitter
Coilless FM transmitter The RF oscillator using the inverter N2 and 10.7Mhz ceramic filter is
driving the parallel combination of N4 to N6 through N3.Since these inverters
are in parallel the output impedance will be low so that it can directly drive
an aerial of 1/4th wavelength. Since the output of N4-N6 is square wave there
will be a lot of harmonics in it. The 9th harmonics of 10.7Mhz (96.3Mhz) will
hence be at the center of the FM band .
N1 is working as an audio amplifier. The audio signals from the microphone are
amplified and fed to the varycap diode. The signal varies the capacitance of the
varycap and hence varies the oscillator frequency which produce Frequency
Modulation.
Published on: 2004-08-21 (3805 reads)
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