Adapting RF transmitter to headphone audio input

[eswick]

Hi all. I am currently trying to create an FM transmitter on a breadboard for a project. I am currently using the circuit here: [url]http://www.circuitstoday.com/long-range-fm-transmitter-1[/url].

I have a few questions about this circuit. Firstly, the circuit is set up for a piezoelectric microphone. As I have absolutely no idea where to obtain one of these cheaply (maybe I just haven't looked hard enough?), I would like to adapt this circuit to transmit audio from a headphone jack, preferably the audio output from an iPhone. I am not experienced enough to figure this out on my own, although I have gone through many pages and articles on the internet. The output voltage/amperage from the headphone jack doesn't appear to be quite standard. Also, I'm not sure if the output from the headphone jack is in the same format as the piezoelectric microphone. If anyone could help me out with adapting this circuit for headphone output, it would be [i]extremely[/i] appreciated.

As for my second question; in R1, there are 3 outputs for a resistor. Is that a special resistor? I believe I am missing something.

I would be very grateful for any help on these questions. Thanks!

[electroyas]

As i can understand you are tryiing to send the iphone audio output through headphone jack without any sound comming out. So why do you need a mic? You can send the audio signal comming from the device to the transmitter through some small capacitor for ac coupling only. Safer for the iphone.