ransistor between Amplifier and Oscillator in some tremolos (ex. Schaller)?

[kimelopidaer]

Would anyone care to explain,
does this transistor 'inject' the oscillators' output into the main signal?
Should I be thinking about it in another way?

I've been putting together simple oscillators on the breadboard and trying to modulate the main signal.
I've had some success having them wobble a jfet boost. I've been connecting the oscillator to the Gate in the boost.
I used a Bipolar junction transistor to bridge the osc. into the   

http://topopiccione.atspace.com/pjimages/SchallerTremolo.sch.jpg