which type of oscillator!

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aj_silverthunder

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1)please tell me does this oscillator work
2)i think the oscillator tank in from MV2109 to the L1 inductor! am i right!
3)which type of oscillator is this!
HOW IS THE STABILITY OF THE OSCILLATOR!
PLEASE HELP
AND IS THE CALCULATION OF THE FREQUENCY IS RIGHT!
 

The vari-cap diodes are in series so their total capacitance is half, not double.

You will never know the tuned frequency because you didn't include stray capacitance and you don't know how much is the stray capacitance.

I think the output level from the emitter is very low. The output level from the collector when it had a load resistor was much higher.

The previous version with the output from the collector could drive an RF amplifier better so that you would get into more trouble for causing communications and TV interference.
 

how do u calculate the stray capacitance!
if there is a stray capacitance can u guess how much it would it be!

Added after 25 minutes:

here i have changed as u said check it out!
 

Each piece of wire has stray capacitance. It will take weeks for you to calculate it all.

Then you will need to also calculate all the stray inductances of every piece of wire.

If you built 20 of these simple transmitters then maybe you could guess about the stray capacitance and inductance.

Simply build it and adjust the capacitance until it works properly.

EDIT:
You do not know how to subtract numbers.
Each Vari-cap diode is 30pF. When they are in series their total capacitance is half the value of one. So their total capacitance is 15pf, not 30pf.
 

then u are saying is that this circuit works well.
i can over come the stray capacitance but tuning the oscillator with the help of the pot and when i hear clear sound from my radio,i can stop and it can be fed to RF power amp
 

If you use a cheap FM radio then this FM transmitter will probably overload it and cause the signal to appear all over the dial which is wrong.
 

The FM radio in a cell phone is made as small and as cheap as possible. I think it will be very overloaded by a nearby transmitter circuit.

My hi-fi tuner and car radio are very high quality and are not overloaded by my FM transmitter when it is very close.
 

aj_silverthunder said:
what do u say about TDA7000 receiver!
Click to expand...
It is obsolete since it has not been made for many years. Its performance was horrible because it is missing many of the important parts of a real radio.
 

ya sorry the value of the two MV2109 in series is 15pF
and please tell me should the 15pF in series connected to the base of the 2N2219 should also be added to calculate the frequency!

Added after 49 seconds:

 

It doesn't matter because you did not include the capacitances of the transistor and of the stray capacitances.

Why are you using an old 2N2219 power transistor when the power in this simple circuit is very low?
 

i just need the oscillator to produce a clean signal and a perfect stability and the output of the oscillator will feed to a 10 Watt RF power amplifier!
 

A 10W amplifier probably needs an input of 1W or 2W. But the output of this simple circuit is much too low.
Its output needs to be filtered to be clean.

Do you have a licence to be a radio station? Did they assign a frequency for it?
Did they approve of what you said you will transmit?
Is the circuit certified not to drift its frequency and to have very low harmonics?
 

should i use LC tank circuit of 95Mhz at the output of the oscillator in order to get clean signal with high stability!

Added after 43 seconds:

 

Most clean radio transmitters use a few LC lowpass filters to remove harmonics. A tank might also work.
 



Added after 57 seconds:

will that low pass filter make the 95Mhz signal stable and clear,are the values are right!
 

You cannot calculate values because you don't know the stray capacitance values of your circuit board and of the antenna.
You are not learning this.
 

Now you have an AM transmitter if the oscillator works.

The Pierce crystal oscillators that I have seen use an inverting transistor or FET and some phase-shifting capacitors.
 

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