Please help me understand this Step Down Circuit

[Ysjoelfir]

Hi everyone,
for my next Youtube video I took a chinese corn style LED bulb to bits and discovered an (at least for me) interesting circuit for the power supply.
I actually cant really understand how it works and would really appreciate if someone could help me out here. Attached is the schematic I draw from the circuit.
What I can see is, that the transistor I marked with "1" in the circuit (which is marked "Y" at the case as it is the tiny little SO-28 (?) thingy) should be the main "power" transistor switching the upper winding of the transformer. The other (TO-92) Transistor is marked 3020, but what does that one? On the other hand this looks like something like an darlington array...

I guess the lower winding of the transformer is some sort of feedback winding to provide either a reference voltage or some kind of clock signal? Where does the switching transistor get its clock from anyways? And how is that thing regulated? Is it regulated at all? I am confused... 

Just for reference I attached a picture of the PCB, where I desoldered the transformer and the 4n7 cap.

[Ysjoelfir]

Thanks! That solved it completely!