fm transmitter scematic required

[maxparveen]

happy new year  guys!
please help me.
i want to build a fm transmitter for radio transmission in my college campus and got so many schematics.but i m confused regarding their ranges.actually i need a stereo fm transmitter having a range of minimum 1 km (with in surrounding buildings ).frequency stability is also matters much.please send  me a fine tested circuit .

 

[maxparveen]

com on guys
2 days passed but no reply
please do it

 

[audioguru2]

The circuit you want is illegal in most countries so people don't have it. It causes radio and TV interference.
There are a few 1W FM transmitter kits available from Ramsey and Free Radio Berkley and are used by "radio pirates" who own ships at sea. A few of the newer kits are pretty good.

 

[maxparveen]

i m having license up to 10 watt so no need to be afrraid of and i am having whole equipment to make own pcbs so i dont want to buy a kit.
please forward me a schematic

 

[audioguru2]

This Micromitter project is excellent and is used to transmit from an MP3 player to a car radio. I have seen them in stores. It has an attenuator on its output so remove it and make a 100MHz power amplifier for it.

View attachment 40287

 

[D0T-C0M]

oh I just saw this post. I too would be interested in finding an amplifier for it so I can get at least 500ft range. I live in a rural area and I would like to boradcast my satelitte radio from my house to the garage.

 

[AN920]

The Micromitter has flea power. Only -10dBm out of the chip. To get 1W you will need to amplify at least 40dB and deal with the resulting harmonics!

 

[D0T-C0M]

yeah but I was thinking that because the 1W amp needed 100mW to drive 1W out that with the 10mW or so that the micromitter has (without the attenuator) that I might be able to drive 100-200mW. Anyway i decided to return the micromitter kit and bought the EDM kit the is switchable between 10mW and 100mW which should be more than enough for what I need. From what I've read the signal quality is pretty decent.

 

[AN920]

The output of the Micromitter without the attenuator will be about 0.1mW and not 10mW

 

[D0T-C0M]

ok you are probably right , I was only going by what I read on the diy site.  They said it would put out 20mW but I read somewhere else someone posted that there must have been a typo and at most it would be 10mW.    In any case I think I will be happy with the EDM-TX-110EP I ordered Have you heard of it?

 

[AN920]

I stumbled onto the EDM page while looking for info on the BH chips. I never bought one as I made my own circuit with a BH1417. I looked at their mod meter at one stage and was thinking of getting one but found a surplus meter on ebay. I have seen a lot of post on the EDM transmitter on various boards. Looks like a good tranmitter. You may want to read the reviews on part15us. This is a site dedicated to low power transmitters AM& FM http://www.part15.us/node/691 There is something on the EDM as well

 

[D0T-C0M]

thanks for the heads up. i was quite concerned at first ordering something from south africa but apparently they have a subsiduary in california USA and they are paypal verified since 2001.

 

[jaya000]

Visit here to see more FM transmitters.

http://www.electronics-diy.com/downloads_pdf.php?s=fm_transmitters

Hope this helps!

 

[djdiler]

You have some good schematics on www.pira.cz

 

[AN920]

yeah but I was thinking that because the 1W amp needed 100mW to drive 1W out that with the 10mW or so that the micromitter has (without the attenuator) that I might be able to drive 100-200mW. Anyway i decided to return the micromitter kit and bought the EDM kit the is switchable between 10mW and 100mW which should be more than enough for what I need. From what I've read the signal quality is pretty decent.

Was wondering if you could give us a report when you receive this transmitter?

 

[D0T-C0M]

Was wondering if you could give us a report when you receive this transmitter?

I recieved my EDM transmitter last Wednesday.  It is an awesome little unit. I am so impressed with the sound quality. It really sounds awesome especially when I connect my cd player to it. Sirius Sat Radio sounds alot better too. Seems to have a really great pre-emphasis stage in the input. The treble sounds better and the base sounds better too. What I like the most is it's separate L-R input level POTs so you can fine tune your inputs for better stereo balance and you can adjust MPX value manually so you are capable of using all the the 75Khz deviation band of the FM signal. Anyone who gets this Tx will not be disappointed. The workmanship is excellent and support so far has been really good. fast email responses. You can purchase them through paypal. Once you purchase a unit from EDM they give you access to a private yahoo group which has lots of great info on such as homemade attenuators, antennas etc...

Anyone who wants more info , dont hesistate to contact me.

 

[D0T-C0M]

using the stock whip antenna I did some preliminary range tests. The Tx was installed in the cab of my truck with the antenna running up and down the mirror which isn't the best placement for it but nevertheless I was very happy with the range I received.  using a fairly good quality FM headset I walked down the road and the sound was crystal clear up to about 300 feet after that I started getting some static and the occasional blank spots. On high setting I got crystal clear sound up to 500-600 and after that a bit of static and the occasional blank spot. Keep in mind that the Tx was in the cab of my truck with alot of metal around it.  I have made a custom 50Ohm coax and made a 1/4wave ground plane antenna and I expect the range to be better when I mount this antenna outside the cab of my truck.  I've read that on high setting I can get about 1/8mile.

 

[AN920]

Sounds very promising. Please report again once you finished testing with your new antenna. BTW what other transmitters can you compare the unit against? Can you say which types you tried out before?

 

[AN920]

Have you tried any of the other stock names like Ramsey before?