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ba1404 clock signal , help

Hi guys. I build a FM transmitter based on the ba1404 chip. The problem arises because this chip need a 38Khz crystal for produce a subcarrier signal for the stereo transmition, but that crystal is hard to find. To solve it i programed a PIC16f84 to generate the 38 Khz signal and, depending of what crystal use for the PIC, i could reproduce the 38Khz fecuency more or less exactly. (For example wuth a PIC runing on a 4MHZ crystal a can generate a 38,4 Khz signal). What accurate such signal have to do?

Thanks, and scuse my english. Cheers.

Gula

Reply to
gula
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those guys are in my home town, there may be someone handier to you as they don't ship internationally. (not from their web site atleast)

these guys do though:

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others have reported failure with that approach.

Do DDS maybe? not something I would try for reasons stated above :)

Bye. Jasen

Reply to
Jasen Betts

THe BA1404 is a really noisy chip, and there are so MUCH better One device available commercially - I've now bought about a dozen of them for friends, rellies, others, gifts etc. Great MP3 sound quality, the Audio in jack isn't very good, but still likely better than the ba1404

/mark

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Reply to
Mark F

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Scuse me, but i don't have good english. What means DDS? Cheers

Reply to
gula

'Direct Digital Synthesis'

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Reply to
Michael A. Terrell

"Direct digital synthesis", it's a way to get more frequency precision than the clock provides from a computer-generated wave,

at it's most crude you could make some cycles longer than others so that you get 38 cycles per milisecond. more advanced methods use digital to analogue conversion to make the change appear to occur part-way throgh a cycle.

Bye. Jasen

Reply to
Jasen Betts

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