this circuits is really unstable,i have build it,it dosent works good!

 

Layout and construction is critical at VHF, how did you build it?, and what on?.

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so.. you're one lucky fellow?

 

There are about 150 FM transmitter projects on the internet. The coil in them is almost the same. 5 to 9 turns of wire.

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Uncle $crooge

 

i like this circuit but could you tell me what is the frequency of operation of this circuit . And what are the calculation related to this circuit..

 

I don't know which FM transmitter circuit you are talking about.
The FM broacast band in most of the world is 88MHz to 108MHz.
These FM transmitters can be tuned in that band.

Calculations are difficult because wiring capacitance affects them. The amount of wiring capacitance depends on how the circuit is built and anything conductive nearby.

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Uncle $crooge

 

I don't understand how to make capacitor 6 and cant get the circuit to work. Pleas post the theory.

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thanks for registraion

 

I don't know which circuit you built. If you made it on a breadboard then the high capacitance of all the wires and between all the conductive contacts make it not work. Make it on a compact pcb.

What is "capacitor 6"?

Most simple FM transmitters have a microphone preamp transistor, a Colpitts oscillator transistor and maybe an RF amplifier transistor. The Colpitts oscillator is a common-base transistor and the modulation at its base makes it conduct more and less. When it conducts more and less its capacitance changes that changes the frequency of the oscillator producing FM.

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Uncle $crooge

 

I don't have much money, can you remove parts from a PCB.

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Electronic parts are very inexpensive.
Use parts from a pcb if you can de-solder them and if they are the correct parts.

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Uncle $crooge

 

Can you give me the specifications of this transmitter and the antenna system with transmitter line?

 

i want to a design of Simple FM transmitter(by electroMaster). How calculate value of R1,R2,R3,R4,R5? help me? I'm doing project of circus. reply soon.
mail: dinhkli245@yahoo.com
thaks inf.

 

Your English is horrible.
You need to know simple arithmatic and Ohm's Law to see how the first transistor is biased.

R1 applies about 0.5mA to the JFET in the electret microphone.

The circuit is too simple:
1) Since the tuned circuit is connected to the antenna then the frequency will change if something moves toward the antenna or moves away.
2) Since it does not have a voltage regulator then the frequency will also change as the battery runs down.
3) It will sound awful without high audio frequencies because it does not have pre-emphasis like FM radio stations have.

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Uncle $crooge

 

with R1 applies about 0.5mA. thus, R1=9/0,5=18k but result of R1 =1k.
Can u guide the calculation R2,R3,R4,R5,R6?
Thaks rely soon!