TheNewGuy
Member
Hello Everyone,
Today, I was scouring the web looking at different FM Transmitter circuits that I could build and I came across **broken link removed**:
I happened to have all the parts for it that he used except the 1,000 Ω resistor, so hoping it would work it subsituted it with a 100,000 Ω resistor. I then breadboarded it out took it to the car and tried to tune the radio to the signal. I could hear music, but the quality stunk, and I could barely make out my music (I knew it was my music because I could change the song), but I was still thrilled it worked.![Big Grin :D :D](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
My dad was impressed, and told me to find a circuit that would have better quality audio (because you could barely make out the music), that wouldn't drift, and that wouldn't get us a fat ticket or fine (I live in the US), we could eventually make it into a PCB and use it.
I've looked at several circuits, one I like a lot is AudioGuru's Mod 4 Miniature FM Transmitter (Link for: schematic and thread), but I'm worried that it would transmit to far and get me in trouble. There are several small ones I find, but I don't want the signal to drift (that is why I like the Mod 4 circuit).
I know there is a cornucopia of information on FM/AM Transmitters, but me not yet being a EE Student yet, I need help understanding all this information and figuring out what schematic would be best for this application.
Thanks everyone,
TheNewGuy
Today, I was scouring the web looking at different FM Transmitter circuits that I could build and I came across **broken link removed**:
For what I'm using, the values are:
**broken link removed**
R1 = 1 kohm
R2 = 10 - 100 ohms
C1 = 22 nF
L1 = 6 turns 32 gauge enamel coated wire (.5 mm thickness), 1/4 diameter, close wound on non-conductive form.
L2 = 5 turns 24 gauge enamel coated wire (1 mm thickness), 1 in. diameter, wound around an "AA" type battery with 2 mm space per turn...
Q1 = 2N3904 (using a different transistor will change the frequency)
It is powered by a 5 volt battery, and it gave me 108 Mhz of frequency (which is the last channel in the FM band)
**Make sure all parts are close to each other so it will oscillate.
I happened to have all the parts for it that he used except the 1,000 Ω resistor, so hoping it would work it subsituted it with a 100,000 Ω resistor. I then breadboarded it out took it to the car and tried to tune the radio to the signal. I could hear music, but the quality stunk, and I could barely make out my music (I knew it was my music because I could change the song), but I was still thrilled it worked.
My dad was impressed, and told me to find a circuit that would have better quality audio (because you could barely make out the music), that wouldn't drift, and that wouldn't get us a fat ticket or fine (I live in the US), we could eventually make it into a PCB and use it.
I've looked at several circuits, one I like a lot is AudioGuru's Mod 4 Miniature FM Transmitter (Link for: schematic and thread), but I'm worried that it would transmit to far and get me in trouble. There are several small ones I find, but I don't want the signal to drift (that is why I like the Mod 4 circuit).
I know there is a cornucopia of information on FM/AM Transmitters, but me not yet being a EE Student yet, I need help understanding all this information and figuring out what schematic would be best for this application.
Thanks everyone,
TheNewGuy
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