Raspomh
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FM transmitter for pi3

Mon Jan 16, 2017 3:35 pm

Hello,

Has anyone done a fm transmitter with their pi? I've watched a few video's but can't seem to get anything working... Any help would be greatly appreciated

Thanks , Fran

jamesh
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Re: FM transmitter for pi3

Mon Jan 16, 2017 3:44 pm

Not legal in most parts of the world, so locking.
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Re: FM transmitter for pi3

Mon Jan 16, 2017 3:58 pm

Unlocked as OP would like to update the post to reflect exactly what he is doing, which is not what the post original implied.
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Raspomh
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Re: FM transmitter for pi3

Mon Jan 16, 2017 4:09 pm

Sorry for not being clear,

What id like to do is : make my pi 3 into an FM transmitter so i could play music from my phone through car speakers
I can buy an fm transmitter from Walmart but i thought this be a fun project any help would be appreciated

thanks Fran

B.Goode
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Re: FM transmitter for pi3

Mon Jan 16, 2017 4:14 pm

Looks like the Moderator's initial instinct to Lock this was the right one.

Even if it isn't illegal, it a certainly anti-social. You have no idea where the interference generated by your planned activity might disrupt the legitimate use of radio bandwidth as you drive around.

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Re: FM transmitter for pi3

Mon Jan 16, 2017 4:40 pm

Not sure, you can buy jack plug to FM transmitters for use in cars, very very short range. I presume since you can buy them in places like Walmart, they are legal, at least in the US.

And it appears in the UK

http://www.maplin.co.uk/p/belkin-f8m117 ... tion-n01nr

What is illegal is using just the Pi to output FM on the GPIO or however you do it.
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Raspomh
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Re: FM transmitter for pi3

Mon Jan 16, 2017 5:06 pm

If im correct... this only play's one song at a time...Also you need to have their OS on the sd card which limits my pi

... I have 30 songs I'd like to play one after the other

mattmiller
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Re: FM transmitter for pi3

Mon Jan 16, 2017 5:32 pm

Oh - I see - you wanted a shrink wrapped retail product? :)

ejolson
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Re: FM transmitter for pi3

Mon Jan 16, 2017 5:33 pm

Raspomh wrote:I can buy an fm transmitter from Walmart but i thought this be a fun project any help would be appreciated
There seems to be a whole selection of FM transmitters available for use in cars at Walmart. While the process to get such hardware licensed is bureaucratic enough that only large companies can do business, these transmitters look ideal for connecting to a Raspberry Pi--simply use the audio out.

The main part of the project would be getting a Pi to run reliably in a car and setting up a media player with a reasonable user interface, similar to other media-center-in-a-car projects. In my opinion, a tablet is likely to work better than a Pi for such things. However, for the sake of learning about computers, Linux and technology, using a Pi is much better.

I can't advise on which media player to use. That will, in part, depend on the user interface you choose. The user interface could be as simple as a single button wired to the GPIO (through a suitable resistor) used start and stop the music or as complicated as a touch screen. One idea would be to go with 2 or 3 buttons for the look and feel of an 8-track tape player, though without the mechanical bits--extra points for using recycled parts from an actual 8-track player.

For reliability you need to configure the Pi's software so it can survive sudden power loss. This is usually done by making the operating system image read only. It will be nice to hear updates on your progress. Good luck!

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Re: FM transmitter for pi3

Mon Jan 16, 2017 6:19 pm

Raspomh wrote:Sorry for not being clear,

What id like to do is : make my pi 3 into an FM transmitter so i could play music from my phone through car speakers
I can buy an fm transmitter from Walmart but i thought this be a fun project any help would be appreciated

thanks Fran


My GPS has FM transmitter and I also have a BT-->FM transponder for my phone.
Tape or CD player FM transmitters have been available for decades

If you want to 'roll your own' then Google for FM transmitter chipset such as MAX2606
Unless specified otherwise my response is based on the latest and fully updated Raspbian Stretch w/ Desktop OS.

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Re: FM transmitter for pi3

Mon Jan 16, 2017 6:30 pm

Raspomh wrote:What id like to do is : make my pi 3 into an FM transmitter so i could play music from my phone through car speakers
I can buy an fm transmitter from Walmart but i thought this be a fun project any help would be appreciated
What does the pi have to do with it? You take the headphone output from the phone, assume it has one, and connect to the input of the short range FM transmitter and set that transmitter for an unused frequency, good luck finding one of those if you are in a built out area. You can, of course, substitute the pi for the phone after figuring out how to keep the pi running inside a car. If you want to control the pi which is plugged into the FM transmitter from the phone, that means you have to somehow connect the phone to the pi. That's not an FM transmitter problem, perhaps it's something done with wifi or bluetooth and some software that might not currently exist.

Raspomh
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Re: FM transmitter for pi3

Mon Jan 16, 2017 6:41 pm

Ok ....mabye i need to be even more clear.........

I have tried and tried to get this to work but all i get is an error

https://www.youtube.com/**sensored**

when i try to pair my phone it does say paring is successful.... but in this video it asks for a pin # I do not enter a pin # just type yes when it asks if i want to pair ... when i try to connect my phone like in the video i get an error... any help would be appreciated

i can provide a screenshot if needed

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DougieLawson
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Re: FM transmitter for pi3

Mon Jan 16, 2017 7:30 pm

Raspomh wrote: I have tried and tried to get this to work but all i get is an error

... redacted URL ...
That is 100% illegal in any country which has a licensed radio spectrum.

Time for James to lock this thread permanently.
Last edited by DougieLawson on Mon Jan 16, 2017 8:18 pm, edited 1 time in total.
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Re: FM transmitter for pi3

Mon Jan 16, 2017 7:44 pm

DougieLawson wrote:That is 100% illegal in any country which has a licensed radio spectrum.

Time for James to lock this thread permanently.
As with any teachable moment, we seem to have come to that point in this thread. Rather than panicking, I would kindly suggest to the original poster, please remove the link to that video so we can go on with the discussion how to use a licensed FM transmitter from Walmart to construct a Pi-based in-car entertainment system. To do this, click on the "edit" above the post and simply delete the YouTube link. If the link could be removed from the quote immediately above as well, we'd be back on track.

There must be another video about pairing a phone. The software discussed in the current link is not suitable for use with a Walmart transmitter anyway and simply leaving the pin number blank isn't going to work.

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mahjongg
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Re: FM transmitter for pi3

Mon Jan 16, 2017 10:35 pm

Agreed, all the steps used in this system (using the bluetooth receiver in a PI3, then sending it out as FM) is legal, except for the part where you use PI2FM, which use is ILLEGAL in most countries. The problem is that PI2FM is NOT really an FM transmitter, its a wideband transmitter that just happens to ALSO send out on the FM band AS WELL AS ILLEGAL BANDS!

You cannot do much to prevent that as the generated signal is a series of square waves, not a clean sinusoidal FM signal.

Transmitting on illegal frequencies is in many countries a crime, punishable even with prison sentences, and "sorry I didn't know I broke the law" isn't getting you off (in some countries).

So do not even try.
You can use the software described above to output audio to the PI's AV output, and connect that to a car FM transmitter, that is (most often) completely legal, as such a transmitter is a real FM transmitter and only sends out FM signal in the FM band (it uses a sinusoidal signal, NOT a square wave).

Now locking this thread!

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