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need circuit for stero fm transimiter

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Go to www.google.com and enter in the search box Silicon Chip Micromitter. The 1st link is to their entire project for free.

It is a pretty good FM stereo transmitter with its RF and stereo frequencies crystal-controlled, with phase-locked-loop tuning to different RF frequencies. It has an RF attenuator at it output to limit its range and keep the RF cops happy. A couple of kits are available in Australia and New Zealand.

I don't know of a project for a good FM stereo receiver. It would be complicated to build and adjust. Radio parts would be impossible to find.
Good FM stereo receivers are cheap, buy one. :lol:
 
Got Article?

Hi audioguru,
Would you have the article which was printed in silicon chip magazine about "FM Micromitters"??...apparently its NOT free anymore...i did a google search using "Stereo FM Micromitters" as u said and it does take me to the link but to read all the article they say i have to pay...so was wondering if u have the FULL article or not..if u do...
can i get it??..cos its not free at siliconchip anymore...
Thanks
insulttosanity
 
Thanks Mna!

thanks MNA...i appreciate ur post:)
helped out TONS!
One more thing...i know this transmitter works in the US...can i put a switch in somewhere to make it compatible in Europe too???
thanks a ton guys...
insulttosanity
 
You might need to adjust a resistor of capacitor somewhere to alter the pre-emphasis, does it say anything about this in the manual, if not have a look at the datasheet for the IC.
 
The micromitter cost more to build then the ready made transmitters (with PLL), try Belkin
 
US/EU Compatibility

Hey guys...thanks for the responses...
Im trying to attach the datasheet of BH1417F...if anyone has a clue as to how to operate the ckt so that its compatible --
1. In the US
2. In Europe
I know the current schematic works in the US...can someone look at the datesheet and tell me exactly what to do such that i can make it inter-operable between the US as well as Europe??
Im making this as a gift to my cousins...one of em is in the US one in Europe ..thus the added workload!
I appreciate ur posts a lot..thanks guys...this forum is the best!!
:)
 

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  • bh1417f.pdf
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The Micromitter is designed for Australia and New Zealand that use 50us of pre-emphasis (treble boost) the same as in Europe. For USA and Canada, change the capacitors to ground at pins 2 and 21 to 3.3nF.
 
hey...thanks for the clue....but i was also wondering abt this...
You say that this ckt is for Europe and australia ...but when u go thru the datasheet for the BH1417(2nd Last PAge Actually)....we see that it transmits frequencies from 87.7Mhz onwards in steps of 0.2MHz..i.e.87.7, 87.9,88.1 etc...now, according to my knowledge, these ODD frequencies are used in the US and in Europe they use EVEN frequencies like for eg. 87.8, 88.0, 88.2 etc...is this fact right?....or will the solution u told me about will work in the US and Europe....also..im curious..as im starting out with electronics...how did u figure out the value of the cap(3.3nf) to put at pins 2 and 21..i mean why onyl 3.3nf...is there a formula involved?....if so could u plese tell me audioguru...this is turning out to be more fun than i thot itd be....electronics IS FUN!!! :D
 
Paul Obrien said:
The micromitter cost more to build then the ready made transmitters (with PLL), try Belkin
A link would be helpful.
 
insulttosanity said:
You say that this ckt is for Europe and australia ...but when u go thru the datasheet for the BH1417(2nd Last PAge Actually)....we see that it transmits frequencies from 87.7Mhz onwards in steps of 0.2MHz..i.e.87.7, 87.9,88.1 etc...now, according to my knowledge, these ODD frequencies are used in the US and in Europe they use EVEN frequencies like for eg. 87.8, 88.0, 88.2 etc...is this fact right?
The datasheet says the IC is made for North America. It has a formula to calculate pre-emphasis and shows a circuit that uses pre-emphasis for Europe, Australia and New Zealand's 50us capacitors, not North America's 75us capacitors that I calculated.
Silicon Chip magazine have their project using the BH1417F IC in Australia and New Zealand but obviously using North America's odd RF frequencies. If Europe uses even RF frequencies then this IC and the Micromitter won't work there. ROHM also makes the BH1416F IC that tunes even RF frequencies. 7 are at the top end of Japan's FM broadcast band and 7 are at the bottom of Europe's FM broadcast band.
 
thanks for the reply audioguru...
i have understood that 1416 produces frequencies for europe and 1417 for US...but since these ICs are pin by pin compatible...can i keep the micromitter ckt same and just change the ICs? (keeping in mind the pre-emphasis of course)..will that work?...or do i need an ENTIRELY different ckt for europe?
Also, is there an IC out there which can do BOTH US and Europe frequencies in the same package? :D askin for too much am i?
thanks ..i really appreciate ur help audioguru...u really seem to kno ur stuff...
 
I don't know why Europe has different FM frequencies than US. They are so far from each other that there isn't interference.
Make one pcb and use different ICs and pre-emphasis parts on them for the two parts of the world.
 
i agree i dunno why there had to be differences in the frequencies in the 2 countries...
Is there an IC out there that can take care of both Europe and the US frequencies??
Thanks again audioguru
 
insulttosanity said:
Is there an IC out there that can take care of both Europe and the US frequencies?
The IC used in the Micromitter is designed to transmit sounds from an MP3 player to a car radio only about 2m away.
Not many people ship their car between Europe and the US.
 
hi audioguru
im gonna use the BH1415F for my FM transmitter but since its a serial input device ive decided to use the PIC 18F2580 to provide this serial data..i have never used a PIC before and am doing so this time so that I can learn more about it...im gonna use MPLAB to use C to program the microcontroller...but heres the thing..my C isnt very good:( ...but im willing to learn...where should i start learning C from so that I can become good in programming microcontrollers??
Thanks!
 
insulttosanity said:
hi audioguru
im gonna use the BH1415F for my FM transmitter but since its a serial input device ive decided to use the PIC 18F2580 to provide this serial data..i have never used a PIC before and am doing so this time so that I can learn more about it...im gonna use MPLAB to use C to program the microcontroller...but heres the thing..my C isnt very good:( ...but im willing to learn...where should i start learning C from so that I can become good in programming microcontrollers??

If your C isn't good you may as well learn assembler, it will help you to use C on a PIC anyway - you should also probably start with a simpler PIC, such as the 16F628, which is easier to learn and does everything you want!.

However, the BH1415F is a stereo AUDIO transmitter, NOT suitable for data transmissions - I suggest you use licence free radio modules, check my tutorials for examples.
 
no..im not trying to TRANSMIT DATA from the BH1415...ill be sending serial data input into the BH1415 to be able to select the modulation frequency..the serial logic at pin 17 defines what modulation frequency the IC will output...thats y im using the PIC...if i send in a logic of 5E3 the IC will output 997 or 99.7Mhz ...thats the reason
Well, I wanna do it thru C itself cos ill be using C later on at school too...but not so much assembly...could u point to some good resources on programming PICs thru C ?...I also went thru ur website..its a good one..thanks
 
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