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Cheap Chinese 'Car FM Transmitters'

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Willen

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Hi,
I recently knew that there are very cheap 'Car FM Transmitters' available like- these selling from aliexpress of China. It would be my nice experiment tool for RF (amplifier experiment, antenna experiment etc) and excited to get. A friend working in Qatar as car AC mechanics and he can send me the transmitter. Before buying these, if here are some member who bought already and tested, then the question is for them-

-Does it have real and good stereo channel separation or does it have 'stereo encoder' for transmitter? Or any comments?

Once I bought a cheap MP3 player which was marked as Hi-Fi stereo but it was mono in real. FM transmission quality (Play via Radio) of a simple NOKIA X2-02 is AMAZING! It transmits exactly 100% quality sound within 1 meter, and distance more than 1 meter the stereo function goes disappear.

Do not worry about illegal aspect of RF, I will never cross of the line of the government. I am also working under government field too. :)
 
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I have a different and older model (similar to the Alibaba units you listed) but with similar functions. I use it with the '74 Vette's original AM/FM "Wonder Bar" Mono radio.

Basically, the one I have allows you select and "un-used" FM frequency on your car (or other) radio and then transmit MP3/WMA music on that frequency to your radio. Don't know if it transmits stereo, but I assume it does and, of course, MP3 is stereo.

There is little to control on the transmitter other than its transmission frequency (and, of course, the normal MP3 options). Very few discrete components and, thus, little to "experiment" with.
 
Cheap Chinese electronic products have a range of quality. If you select one item then some work fairly well and others are dead or work very poorly.
The cheap ones have no spec's so maybe they cut high audio frequencies, produce awful distortion, are noisy or have poor stereo channel separation.
 
The one I had used the BA1404 See **broken link removed**
I tried to get BA1404 IC, its more advance IC BH1417 around me. I found never.

Do they use same type of chip or any modern replacement chip (FM Tx chip) in such Car FM Tx? I think they use their own built-in Tx chip.
 
The old Japanese BA1404 produced so many problems that it was replaced by the modern BH1417 and its sisters. The BH1417 worked very well but is not made anymore because not enough of them were bought.
Maybe today a Cheap Chinese company makes a copy of the BA1417.
 
A lot of people complained about the poor performance of the old BA1404 IC in one of Ramsey's old FM stereo transmitter kits. They still might sell it.
 
YES! How cheap FM transmitter I found with transmitting frequency (MHz) display and with USB/SD card reader! I never expected that I can get such device in my near city in Nepal! :) It costs just Rs.380/- (US$3.8)! It has a remote controller from where we can increase and decrease transmitting frequency, control audio (Next, Prev, Pause), Vol+-, Equilizer etc. The device is called "Car FM transmitter/modulator".

Overall audio is not bad (nice for me)! It has no stereo encoder and no channel separation however it's not mono, it sounds like surround sound. Actually it has fake stereo effect which sounds like audio are circulating around our ears (but not stereo). Audio is very crisp (depends on Equilizer). Frequency stability is amazingly stable! Display is not VERY accurate though. The transmitter is displaying 88.2MHz but my cellphone is getting its signal at 88.1MHz. It's OK because it costs just US$3.8! (probably the designer did not calculate the probable 'stray capacitance' so the transmitted frequency has been drifted).

Input voltage is regulated by 78M05 (SMD) so input voltage is around 7V to 12V. Total current consumption is around 90mA. Transmitting range is around 15 to 20 meter (it has no antenna) but simply I can increase range by adding 30 inch wire as antenna. Or I can add a RF amplifier to it to get hundreds of meters (or KMs) of range!

One of the most Exciting thing is that we can use any type of AC to DC adaptors as power supply like a linear transformer, SMPS however it 'DO NOT' produce any noises generated by 50Hz line noise hum or switching noises from SMPS, Wow!

Inside of the device an IC has been patched in PCB, and 12.000 xtal exist and 'j8' (S9018) transistor has been added as RF booster.
 

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There are many pretty good FM transmitters for cars sold here. They are all stereo, have excellent frequency stability since they use a crystal controlled synthesizer and have low distortion and noise.
 
Why would you want to transmit sound from a radio when you can turn the radio sound up and listen to it?
 
Why would you want to transmit sound from a radio when you can turn the radio sound up and listen to it?
Actually I am a hobbyist and you know that hobbyists work for unnecessary thing most of the time. :) I am addicted to RF electronics. FM transmitters are amazing thing for me from my starting of electronics career till now. Radio transmission through 'wireless' is amazing.
 
Gary:
Two uses:
1) add an MP3 Player/CD player/Handsfree phone
2) To keep a classic car looking classic

The other method is using a cassette with a head in it.
 
Actually I am a hobbyist and you know that hobbyists work for unnecessary thing most of the time. :) I am addicted to RF electronics. FM transmitters are amazing thing for me from my starting of electronics career till now. Radio transmission through 'wireless' is amazing.

YES I know what your saying I do the same thing. I once had 7 Tesla Coils each one larger than the last. Lots of fun project, fun to build but not very useful.
 
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