Circuit diagram to modulate carrier with audio signal using transistor

guys

I built a stand-alone colpitts oscillator to generate carrier wave
Now i want to make a frequency modulator circuit with the help of transistor but no idea to modulate the signal with carrier
plz give me circuit diagram to modulate carrier with audio signal using transistor

Dear aevis
Hi
Can you attach your schematic ? is the feed back path from collector to the emitter ?
If yes , it is pretty simple . you can use from miller effect on internal capacitors in transistor to create an FM signal , simply .
Best Wishes
Goldsmith

humm ! you can give your signal into , base or emitter . thus , the internal capacitors of your transistor will change instead of variations of your audio signal simply .
Good luck
Goldsmith

The easy way to get a pure FM modulator is to use a varicap diode placed in the oscillator resonant circuit, and the varicap to be modulated by the modulation signal.
You can modulate directly the BE junction of the transistor, but in this situation the modulator is mainly a Phase Modulator (PM). At some point this will not make big difference for simple circuits like this.