I have drawn the above schematic by reverse engineering a locally available LED Bulb. I was expecting to find an IC in the driver board but instead found this discrete circuit.
Googling "Discrete LED Driver" does not return a lot of relevant hits. From my understanding, I think C4 and L1 form a tanked circuit which drives the base at startup. Once the collector is pulled low, a voltage is induced on L1 via L2 and this cycle continues (?).
I do not understand how this circuit is regulating it's current through the LEDs as it is a constant current driver.
I am hoping someone more experienced here could explain the workings of this circuit to me.
Some info I left out: The output voltage can go upto 94V and the current is a steady 133 mA.