Hi Manz,
I clicked on Attachment, then Browse, then selected my pic file, then clicked Open, then either Preview and I see my pic then Submit, or just Submit and it works. If your pic file is a BMP, then convert it to a JPG file type in your viewer program before attaching it.
The coil on the left determines the oscillator's frequency by its number of turns, wire size, turns spacing, and diameter of the coil. It resonates with the trimmer capacitor across it plus stray capacitance of the wiring, capacitance of the transistor, feedback capacitor and capacitance to anything nearby.
The coil on the right determines the RF amplifier's frequency the same as above, and should have its trimmer capacitor adjusted for peak output level for maximum range. The tuning of the RF amplifier is very broad and covers about half the entire FM band.
If car radios cause acoustical feedback then the radio is too loud or the transmitter is too close to it. My project has high preamp gain so its microphone can pick-up sounds quite far away. :lol: