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The eight switches are the pins of an integrated circuit. The 1μF capacitor is an unmarked surface mount capacitor of unknown capacitance. The 100mH inductor is a coil of wire in what appears to be a transformer housing (it’s looks like the same housing as the 300mH:3mH, 10:1 transformer in my Electronic Playground) of unknown value. I have chosen the values of 1μF and 100mH for these components arbitrarily as I do not know the true value. The three other capacitors are all of 250V rating with the two 10μF capacitors being identical. The 400μH inductor has a shape similar to a capacitor but with a ferrite core and “0.4mH” on the side.
The big inductor has “*C2GO.8” (or maybe “*C2G0.8”) written on top with the asterisk being a circle similar to a period but at the top of the line instead of the bottom. I’ve put this code into google (without the asterisk) but there were no relevant results.
The 8 pin IC has these three lines written on it:
BP9916E
J6B74KX
SA46X
Googling the first line led me to this data sheet: http://www.bpsemi.com/uploads/file/20161124110238_603.pdf which informs me that the next two lines are lot code and date which explains why googling them didn’t bring anything relevant up. However, the lot code and date don’t follow the format given in the data sheet, so perhaps this one was made by a different manufacturer.
The data sheet says “BP9916E is a high precision Buck constant current LED driver” and mentions a power MOSFET, so it seems to be the switching part of a switching buck converter. However, the pin connections seem to be strange with only three connections: GND/CS (ground/current sense) which is connected to the four pins on the left, DRAIN which is the upper right pin, and VCC which is the lower right pin, and the other two are unconnected. Does anyone know why it doesn’t have separate GND and CS pins, or how it even senses current without a separate GND pin? It seems possible if it makes use of the capacitor at VCC to provide a stable voltage reference, but that seems unnecessarily complicated. Why not just have one of the unconnected pins serve as a ground reference?
Also, what’s the purpose of the 400μH inductor? It appears to be part of a pi filter, but with a cutoff frequency of 3 or 4 kHz it doesn’t seem very useful for filtering the 120Hz rectified signal.
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