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-   -   Broadcasting level hifi audio FM transmitter (http://www.diyaudio.com/forums/siliconray-online-electronics-store/212280-broadcasting-level-hifi-audio-fm-transmitter.html)

siliconray 7th May 2012 12:46 PM

Broadcasting level hifi audio FM transmitter
 
If you are looking for a real high sound quality stereo FM audio transmitter at a reasonable price, the VMR6512 is second to none. It's also developed by me in 2011. 380k have been sold till last month. It works from 88-108MHz or 76-108MHz, frequency can be set by button or serial port in 0.1MHz step. Power is high enough to be received at 100 meters away (in open air). Moreover, it even has digital audio interface! Most customers use it in wireless headphone and in car MP3 transmitters.

VMR6512 hifi stereo FM audio transmitter

http://www.siliconray.com/media/cata...rd_vmr6512.jpg

AndrewT 7th May 2012 12:48 PM

Do you know which countries permit operation of this or similar transmitters?

What you are suggesting may be illegal in some/many countries.

siliconray 7th May 2012 12:50 PM

all countries permit this freq at this power (6mw). I also developed a power amplifier VMR6700 for it, but it really cause leagal problems. There're at least 100k of this module in the USA, most are bought by equipment companies.

AndrewT 7th May 2012 12:51 PM

100m and what power?

siliconray 7th May 2012 12:56 PM

less than 6mw

siliconray 7th May 2012 12:57 PM

Oh sorry..default power is 6mw. It's adjustable up to 10mW by serial port.

siliconray 7th May 2012 01:41 PM

It is funny, do you also report on semiconductor make illegal transistors because it can be used to make illegal rd amplifiers

godfrey 7th May 2012 02:42 PM

I don't see any coils or capacitors in the circuit. Is the output just a digitally generated square wave? If so, isn't there a problem with interference from the harmonics? e.g. If you're transmitting at 100MHz, won't there also be significant output at 300MHz etc?

On second thoughts, I suppose the unwanted radiation will be too weak to interfere with TV, Police, ATC or whatever's on the higher frequency (too lazy to look it up).

[ot]
low power transmitters are fun! I think that's about the first thing I made as a kid when somebody gave me my first transistor.
[/ot]

p.s. I bet you can get a lot further than 100m with even a half-decent antenna. :devily:

yajnaS 7th May 2012 02:45 PM

Isn't this the standard chip (with 10s of Taiwan clones) that comes in Cigarette lighter mp3 FM transmitters ?

How is your product better, given that this is a single chip solution, and the only thing you could possibly do is put in some fancy regulator ?

siliconray 7th May 2012 02:54 PM

There're SMD coils inside the module. The spectrum of this module is very pure since it has PLL circuit. 10mW has no harm to any other applications. The distance could be longer with better antenna, and it depends largely on the snesitivity of receiver.

Yajnas, besides the sound quality, have you ever seen a Taiwan or Chinese clone mp3 FM transmitter with digital audio interface and can adjust frequency, power, pre-emp and mute via serial port? It's not the simple IC like BA1407


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