Hi all,


I’m working on a small FM transmitter project using a Raspberry Pi 3 and the fm_transmitter library by markondej (GitHub link: https://github.com/markondej/fm_transmitter). It uses a GPIO pin to output a square wave FM signal directly.


The output is around 3.3V and can only safely source about 16mA — anything more risks damaging the Pi. I also know the signal is quite dirty with a lot of harmonics due to the square wave output.


I’d like to amplify the signal to get better range while staying within safe operating limits for the Pi. I'm also interested in cleaning up the signal (some kind of filtering maybe?).


Has anyone done this successfully? Are there low-power RF amplifier circuits or modules that work well with this kind of signal? Ideally something I can build or buy cheaply.


Any suggestions or warnings would be much appreciated!


Thanks!

 

Wecome to AAC!
Are you aware of the limitations on wireless transmission for your proposed project to be legal?

 

Hi all,


I’m working on a small FM transmitter project using a Raspberry Pi 3 and the fm_transmitter library by markondej (GitHub link: https://github.com/markondej/fm_transmitter). It uses a GPIO pin to output a square wave FM signal directly.


The output is around 3.3V and can only safely source about 16mA — anything more risks damaging the Pi. I also know the signal is quite dirty with a lot of harmonics due to the square wave output.


I’d like to amplify the signal to get better range while staying within safe operating limits for the Pi. I'm also interested in cleaning up the signal (some kind of filtering maybe?).


Has anyone done this successfully? Are there low-power RF amplifier circuits or modules that work well with this kind of signal? Ideally something I can build or buy cheaply.


Any suggestions or warnings would be much appreciated!


Thanks!

Only one suggestion or warning. Don't do it. If you want to play with radio transmission, get a proper license.


From your link:

Legal note
Please keep in mind that transmitting on certain frequencies without special permissions may be illegal in your country.