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Can I make FM modulation using 74ls124?

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mr_byte31

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FM using an IC

can i amke FM modulation using 74ls124?
if yes how can i make an effecient transmitter using it?
 

Re: FM using an IC

The maximum frequency of the 74ls124 VCO is about 30MHz. So if you need a transmitter in the FM broadcast band, you need a bandpass filter tuned to a VCO harmonic.
As an RC oscillator, 74ls124 is not very stable and may be very noisy to use as an FM modulator. The control and power voltage should be very well filtered, else the power supply noise and ac hum will modulate the tranmitter.
The VCO frequency deviation is about 5MHz/volt and on the 3rd harmonic is multiplied to 15MHz/V. Wideband FM uses 75kHz deviation, so the peak modulation voltage would be 75k/5M = 15mV!!!!!!!!
Use an LC oscillator, is more stable and clean. I think 74LS124 cant be used here.
 

Re: FM using an IC

then how can i make a satable oscillator generating a pure sine wave
and with varaible frequency
 

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