FM transmitter using BA1404

Thread Starter

arunpradh

Joined Dec 11, 2013
55
i want to make an fm transmitter with ba1404 as modulator.
the 38 khz crystal is not avilable in the market.

can i use 32.768 khz watch crystal insted of 38 khz?

what is the role of this crystal? is this one is responsible for transmitting frequency?

some body help me................
:confused::confused::confused::confused::confused:
 

crutschow

Joined Mar 14, 2008
34,280
You must use a 38kHz crystal. That's the frequency of the multiplexer for the stereo signal. If the transmitter frequency is not that value then the receiver cannot decode the stereo signal and the sound will be monophonic.
 

AnalogKid

Joined Aug 1, 2013
10,986
Think about the BH1417 chip instead. It is a later generation part with better sound, and uses a 7.6 MHz crystal to digitally synthesize the carrier and directly derive the 38 KHz pilot tone. I was going to build some, then found assembled circuits on ebay for about $5 each.

If you really want to build from scratch, Mouser has the crystal for 50 cents.

ak
 

wmodavis

Joined Oct 23, 2010
739
1. Yes you can use a 2N2222 as an amplifier.

2. Maybe. But "higher power"? Higher than what? Are you asking about increasing the power output of the ba 1404? If so - how much power output does the ba 1404 have? What frequency are you talking about? What is the capability of the 2n2222 at that frequency?

More questions than answers because you didn't clearly state what you really want or provide a schematic of what you have/want/propose so someone could provide a helpful answer without lots of guessing. I'm not a good guesser.
 

alfacliff

Joined Dec 13, 2013
2,458
according to the spec on the ba1404, it has only 600 nanovolts coming out at 50kohm impedance. an amplifier could be built, but it would be a lot more complex than just a 2n2222.
 

alfacliff

Joined Dec 13, 2013
2,458
the spec sheet I was reading was a bit fuzzier. a 2n2222 would work for this chip, you would not even need to bias the chip, since fm does not need linear amplification like am or ssb.
 

Thread Starter

arunpradh

Joined Dec 11, 2013
55
i constructed the circuit of ba 1404 fm transmitter and it worked. i used 32.768 Khz crystal insted of 38 Khz. the circuit worked , i didnt checked the stereo separation. but it works. another fact is that when i removed the crystal the transmitter is still working.
below is the schematics.
http://www.electroschematics.com/wp-content/uploads/2009/09/ba1404-stereo-transmitter.jpg

please some one help me to design an rf amp for it to increase its range.
i saw a circuit which uses upc1675 as rf amplifier
 

bertus

Joined Apr 5, 2008
22,270
Hello,

I have merged ALL 6 threads about your FM transmitter into one thread.
You do NOT need to start a new thread for every question about the FM transmitter.
The large number of threads will only create confusion.

Bertus
 

Thread Starter

arunpradh

Joined Dec 11, 2013
55
i need suggestions for the selection of a transistor to make an rf amplifier for transmission of 90-99.9 Mhz (F.M).

i also need the points to ponder while dealing with this .
 

BR-549

Joined Sep 22, 2013
4,928
I am assuming because of the frequency range....this is a very low pwr amp. If this is true....you can buy very small boards with everything you need.......just attach 9 volt battery and mike.......for a couple of dollars. Search for mini fm transmitters. The older ones are discrete and you can experiment with them. The newer ones are just one IC.
 
Top