This is a minimalist FM transmitter I've found from http://www.talkingelectronics.com/projects/Spy%20Circuits/SpyCircuits-1.html
I'm a bit confuse about three things
1)How does this modulates the base input signal to frequency modulation ? Because I don't see any change happening neither in Inductance nor in Capacitance of that LC tank oscillator. Is that because of C1 somehow ?
2) For what purpose capacitor C5 is used ?