fm transmitter simulation

[BrownOut]

Those preamp transistor used in most transmitter have voltage gains of between 20 and 100. Mod4 has a dc voltage gain of about 21. Not 4v p-p, but much closer than 20mV. Either way as stated, the levels demonstrate the results of FM techniques. You can't hear FM, so listening won't do any good. Might as well turn up the gain and frequency so you can see what's going on. After all, what's teh worse that can happen? He might *gasp* learn something?

 

[Sceadwian]

You can find out what kind of modulation you're getting and how much by doing an FFT on that point. LTSpice has many advanced FFT options.

 

[BrownOut]

I'm afraid there are way too many artifacts in the signal for the FFT to be effective in determining the deviation. I estimate a few hundred Khz deviation, nowhere near the 75Mhz previously mentioned. So what if that violates the 75Khz spec? The idea was to observe some frequency modulation, not to try to transmit the signal. I think we've accomplised that. The low-level modulation that isn't observable is done the same way.

I'm used to operating circuits outside their normal limits to learn what's going on with them. Indeed, I bring my high voltage projects up from voltages much, much lower than spec so I can keep a watch on the critical values while I crank up the power.

 

[rahul.sadtm]

thanks a lot....

thanks Eric... thanks Brown... and thanks to all the team...

circuit simulation and the hardware is successfully completed...

 

[fvm]

guys
circuit in this thread is not of multiplex FM transmitter...right???