[sdiy] discrete circuit question:

[Nils Pipenbrinck]

Please take a look at this circuit:

http://forum.musikding.de/attachements/Trem.gif

(It's from the guts of a single transistor chopper style tremol circuit).

What role does the diode and the series resistor play? My guess is, that 
the diode protects the basis-emitter junction of the tranny in case 
there is a large signal swing that could possible permanently damage the 
BE-junction   If so - why the series resistor? I doubt the leakage 
current of the diode would make any difference at all, so in my oppinion 
the resistor is useless.

I have a discussion about that little detail on a guitar fx forum, and 
we're a bit stuck, so I thought I'd rather ask here.

Thanks,
  Nils