help about fm transmitter analysis

[shazdek0ch0l0]

output waveform of a fm transmitter

Is there any engineer that knows how does this circuit work?
In the other word I want the output waveform of this circuit and manually analysis of this; if anybody helps me I will be very thankful
I wait!
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[vfone]

fm transmitter analises

Q2 suppose to be a high-frequency Colpitts oscillator, with output frequency modulated by the 1kHz frequency which is amplified by the Q1.
Anyway, Q2 will never oscillate with the component values that you have (C5=1uF in parallel with C3=5pF !!??)

 

[shazdek0ch0l0]

fm waveform

1st of all thank u for help
i think the source "V2" should have 1MegHz frequency but i,m not sure, because it is the model of microphone; what should be the frequency of microphone?

and about c3: it is only to get a bit of tuning out of the coil ,and in notes of this circuir wrote :you can put it 4-40pF trimmer capacitor (optional) parallel over L1

Added after 3 minutes:

i hope u and other engineers help me to solve this problem

i want to know what is the output waveform and how i can analys that!
i will be very thankfull

 

[vfone]

transmitter analysis circuit

V2 for microphone simulation should be 1kHz.
C5 shouldn’t be in parallel with L1 and C3. Place C5 between V1 and ground.
To resonate on FM broadcast band 88-108MHz, L1 shall be approximately 100nH and use for C3 a trim cap as you said 4-40pF.

You need a simulation software to see the output waveform. Check the net, there are few freeware Spice simulators.

 

[shazdek0ch0l0]

i use "circuit maker" for seeing output waveform.but
can you plz tell me, what is the formula of output voltage in this circuit?

 

[shazdek0ch0l0]

Thank you, with L=100nH, the output voltage being like below (I think if c5 place between v1 and ground, it will be in parallel with c1)
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And with my elements, the output is:
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And in both of them, I cannot see FM shape?! because i heard the shape of FM is like below. Why these occur? And which of them is correct?

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[shazdek0ch0l0]

Is there anybody to answer my Question?

Added after 3 minutes:

i correct the value of V2 to 6mV and i get sinusian wave, but it's not FM,yet.
what can i do??

plz answer to my question

Added after 2 minutes:

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[vfone]

Looking to the timing of your simulation, seems that your RF oscillator (Q2) is not oscillating. What you see is the 1kHz generated by the signal generator.
Remove C2 from your schematic and check if get any RF oscillation at the output of Q2. By the way, why you are not choosing real transistors for Q1 and Q2 from the library.

 

[BigBoss]

Qulality Factor of the tank circuit is too bad..
1uH//5pF is not good choice.Instead, L should be as low as possible, C should be much more higher.Therefore Osc circuit doesn't start to oscillate...
You may also find more suitable FM transmiiter circuits on the internet such as Varicap FM modulated with buffer transmitter amplifer etc.

 

[shazdek0ch0l0]

but i cant see the correct output,yet

can u show me the correct output, u know?