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Circuits > RF circuit > Coil-less FM Transmitter
Coil-less 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.
Title: Coil-less FM Transmitter
Source: unknown
Published on: 2005-08-27
Reads: 1286
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