I need Fm Transmitter of 1 Watt

[arevindh]

I need Fm Transmitter Circuit :roll:

1.1W o/p power
2.high frequency stability
3.price - low
4.12 v DC supply

 

[betwixt]

At what frequency ???
Brian.

 

[arevindh]

At what frequency ???
Brian.

I need it to operate in the 97.9 Mhz freaquancy

 

[vinodstanur]

1 Watt FM Transmitter

 

[arevindh]

1 Watt FM Transmitter[/QUOTE]
Could it give a better frequency stability ?

 

[betwixt]

You could derive the tuning voltage, currently taken from the wiper of the potentiometer, from a PLL instead and lock it to a quartz crystal. That would give excellent stability but would need a few more components. If you use the PLL method, be sure the loop filter response is slow enough that it doesn't 'fight' against your modulation voltage. If built properly, the circuit should be fairly stable as it is though. It is a well thought out design and has voltage stabilization where it is needed. You might be able to leave the 5V regulator out and connect the tuning voltage supply to pin 3 of the 9V regulator instead to save a few parts.

Brian.

 

[arevindh]

You could derive the tuning voltage, currently taken from the wiper of the potentiometer, from a PLL instead and lock it to a quartz crystal. That would give excellent stability but would need a few more components. If you use the PLL method, be sure the loop filter response is slow enough that it doesn't 'fight' against your modulation voltage. If built properly, the circuit should be fairly stable as it is though. It is a well thought out design and has voltage stabilization where it is needed. You might be able to leave the 5V regulator out and connect the tuning voltage supply to pin 3 of the 9V regulator instead to save a few parts.
Brian.

Friend ,
I tried this with a FM Transmitter bought from a nearest store mfd by " SILICONICS " .But the was a humming voice with transmitted signal. Can I eliminate this ?

 

[pranam77]

Friend , I tried this with a FM Transmitter bought from a nearest store mfd by " SILICONICS " .But the was a humming voice with transmitted signal. Can I eliminate this ?

For smooth transmission, ensure that your supply is well filtered or use a battery for better performance. Frequency stability depends highly on the power supply, quality of components used, the material of PCB, and the PCB layout too. Cheers

 

[sanjubluerock3]

The mod4 fm tx is more reliable and is working fine for me

and frequency u can adjust using variable cap...

or try with vegakit....they have DIY kits available...

 

[arevindh]

I have attached a file of FM transmitter I bought is PCB Layout by me is also in it (Sorry for the circuit is not well imaged ) It can be opened using Targe3001 V14

 

[sanjubluerock3]

please upload in pdf format so that every can view it easily boss....

did u try building the mod4 design by audioguru????

 

[pranam77]

(Sorry for the circuit is not well imaged ) It can be opened using Targe3001 V14

Always stick to commonly used extensions like JPG, BMP. PDF, TIF, ZiF, RAR etc so that your upload can be viewed and utilised by the needy. OR if you are posting any image from a webpage, just posting the links will be fine.

 

[amjadali56]

what about this one?

 

[betwixt]

That should work nicely, even if it is a bit larger and fragile than it could be. It has some nice features, like having the three inductors on different axis. I would place an electrolytic capacitor across the point where power is connected, suggest 100uF, to help with LF stability. Be careful if a heat sink is needed on the output transistor, it could easily touch other parts and the transistor tab is not isolated.

Brian.

 

[arevindh]

Always stick to commonly used extensions like JPG, BMP. PDF, TIF, ZiF, RAR etc so that your upload can be viewed and utilised by the needy. OR if you are posting any image from a webpage, just posting the links will be fine.

Given below is the jpg image

:arrow:
Its frequency changes as battery voltage decrease :?:?:?.1 use 8 Rechargeable Ni-Cd Cells to power it can i connect a voltage regulator IC 7806 or 7809 to it ????:-o:-o

---------- Post added at 14:17 ---------- Previous post was at 14:11 ----------

please upload in pdf format so that every can view it easily boss....

did u try building the mod4 design by audioguru????

No i didn't . I have Uploaded jpg image of it pls see it

 

[betwixt]

What on Earth was used to draw that !!!

The design has several flaws and I would expect it to change frequency as the supply varied. Look at the earlier schematic and see where the voltage regulators are connected.
I assume from R5 and the lack of pre-emphasis that this is designed to be fed from an electret microphone, is it supposed to be a 'stage microphone' ?

Brian.

 

[amjadali56]

some good text about RF
need some more? glade to help.

 

[ZASto]

For a design that WORKS take a look at Pira.cz - Local radio, Broadcast equipment, Schematics, Photos

 

[Enlightenment]

For all amplifiers / RF circuits / analog circuit, shielding is critical. Companies don't put those things in metal enclosures for no reason!

If you build one of these things and put it in a plastic enclosure, then you deserve to have problems.

 

[amjadali56]

modification in last posted diagram "FM88"