FM transmitter

[inmate]

i am fairly new to electronics i know what most of the common components do and can solder but have no clue how to begin when it comes to designing circuits or adapting them to my uses i want to build a transmitter to play music from my mp3 over the radio in stereo sound i found this circuit (https://www.aaroncake.net/circuits/fmtrans.htm)
**broken link removed**

I want to know how to replace the mic with a headphone jack and if it would allow my to play the music in stereo

 

[mramos1]

Many of the units on the internet show the output (mono in your case, one
of the channels) through a pot (input level control) connected where the mic is. I would add a small cap as well, as the circuit puts DC across your output through R6 for the mic.

Better idea, google for FM stereo transmitter circuit and get one designed for doing what you are trying to do rather than take a chance on breaking your MP3 player?

 

[Hero999]

That transmitter isn't very good try audioguru's transmitter.
**broken link removed**

 

[audioguru]

The Micromitter is a good quality FM stereo transmitter. Many are in stores. A guy replied that he bought one for $4.00 and I have seen them for $19.00.

 

[inmate]

on audioguru's transmitter there is still power going across the mic correct?
on the Micromitter what are the 4 switches for and where is the frequency adjustment.

 

[3v0]

I was interested in looking at what the power output was but the info got me thinking (daydreaming) about applications.

Did not see matching receivers

DigiKey has it in a surface mount package about $4US
BH1417F-E2CT-ND BH1417F-E2
IC TRANSMITTER FM STERO SOP22 Rohm

**broken link removed**

They also sell the BH1414K-E2 in quan 1 but have none in stock.

The BH1414K allows the transmission frequency as well as the input level setting, monaural operation, output on-off and EVR (Electronics Volume Reduction) to be changed with a serial data link from a microprocessor.

Digikey about $7US
BH1414K-E2DKR-ND BH1414K-E2
IC TRANSMITTER FM STEREO QFP44

3v0

 

[audioguru]

My FM transmitter has a very sensitive microphone input with power through a resistor to power the microphone. It is mono, not stereo. Delete the rsistor if an electret microphone is not used.

You could mix stereo to make mono with two resistors then use a 3rd resistor as an attenuator to use an MP3 player as an input.

Very accurate FM radio frequencies are selected with the 4 switches in the Micromitter.The entire Micromitter project is here:
https://electronics-diy.com/schematics/BH1417_fm_transmitter.htm

 

[inmate]

audioguru if i wanted to use your transmiter i would take out the resistor r1 but leave c1 and just put the audio input where the mic is?
also could you explain how to mix the audio I am looking for as simple of a project as i can the micromitter looks great but it also looks complecated and i want to build a fiew more simple projects before i try a more complicated one

 

[Nigel Goodwin]

audioguru if i wanted to use your transmiter i would take out the resistor r1 but leave c1 and just put the audio input where the mic is

Yes, but attenuate it to mike level like he said, a line input directly will over modulate it.

 

[audioguru]

Here is a three-resistors mixer and attenuator to connect stereo to my transmitter instead of R1 and a microphone:

 

[Hero999]

Am I the only one getting bored of these FM transmitter threads?

If you ever get bored Nigel, perhaps you could merge them all together to form one big fat FM transmitter thread.

 

[audioguru]

The same FM transmitter questions over and over and over and ....