your fm transmiter is very good,bravo and sorry for bad words...

 

well,I'm going to build this one.

 

Hi,

If you are looking for more ideas about building FM transmitters, look here:

http://pira.cz/eng/

PiRa = Pirate Radio

I haven't built any transmitter from that site but I believe it would work - just be careful that operating such transmitters can be illegal ...

There is a description on that site of a very simple frequency counter which I have built a few years ago and it works very well so I believe the transmitters would work as well.

Petr

 

What kind of board is your circuit assembled on? I have never seen one like that. Is it soldered or wire wrapped? It looks really cool.

 

My FM transmitter is made on Stripboard. It is perforated and has parallel copper strips. The copper strips are cut at a hole then the remainder of the strip is used for another part of the circuit. The strips make half a pcb and the parts and a few jumper wires make the remainder of the pcb. Each hole has a single wire in it.

Attached Images

FM tx mod4 pic.jpg (44.7 KB, 44 views)

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Uncle $crooge

 

Hi all,

I am going to construct the FM transmitter according to following schematics using veroboard : Miniature FM Transmitter #4 from Atoon website (the right most pictures in the 1 post of this thread)

As far as I know, components layout is very critical in RF circuit. Anyone has experience in this, please help.

Your support would be much appreciated. Thanks!

 

It is not a good FM transmitter:
1) Its antenna is connected to its oscillator so its frequency will change if something gets near the antenna or moves away.
2) It doesn't have a voltage regulator so its frequency will also change as the battery runs down.
3) It doesn't have pre-emphasis (treble boost) like all FM radio stations so the de-emphasis in all FM radios will cut the highs and sound like a stereo with its treble tone control turned all the way down, or like an AM radio.
4) It is mono, not stereo like a Micromitter.

I made the very simple circuit about 45 years ago. Its performance was poor.

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Uncle $crooge

 

How about the Miniature FM transmitter #1 (Atoon website)
Let's say actually I don't really concern about sound quality as well as power supply, then are there anything else I should pay attention to?
For the antenna problem, do you mean I should place the atenna far way from the trimmer capacitor?
Thanks!

 

The antenna of the very simple FM transmitter is connected directly to the oscillators tuned circuit. Anything that gets near the antenna or moves away changes the capacitance at the antenna and at the oscillator's tuned circuit which changes the oscillator's frequency.
My FM transmitter has an RF amplifier between the oscillator and the antenna so its frequency does not change.

It doesn;t have a voltage regulator like my circuit so you must retune it as the battery runs down.

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Uncle $crooge

 

I'd like to see the backside of this. Would you post a photo of it?

 

I made my FM transmitter 3.5 years ago.
The stripboard is just 12 horizontal parallel strips of copper. Some of the strips were cut with a drill bit and so the strip was used for two or three functions. Eadh part has its own holes. A few vertical jumper wires are on the parts side of the stripboard. Most of the parts are also vertical.

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Uncle $crooge

 

Hi.
I built FM Well.
http://www.pira.cz/tx4.htm

 

Sir,
Thanks for ur circuit,
does it work well
does it need an antenna

 

I was not knighted by the Queen of England so I am not a SIR.

My Mod-4 FM transmitter sounds excellent, its frequency does not change when something move near or moves away from its antenna nor when the battery voltage runs down and its range is more than 2km to a very sensitive FM receiver when its 9V alkaline battery is new and there is nothing in between.

Of course it needs an antenna. It is a radio transmitter.
I never tried it without an antenna.
Without an antenna then its range might be across the street if it is in a plastic box.
I tried it without a battery but it didn't work.

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Uncle $crooge

 

Nice reply Audioguru.

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Regards,
Sarma.